From 9c7a61f681b9afa8ee1f9445ce52fdf5cfbaeb45 Mon Sep 17 00:00:00 2001
From: NaBian <836904362@qq.com>
Date: Tue, 19 Jan 2021 18:30:35 +0800
Subject: [PATCH] update CheckComboBox Style with Empty control

---
 .../Styles/Base/CheckComboBoxBaseStyle.xaml   | 180 ++++++++--------
 .../Themes/Styles/Base/ComboBoxBaseStyle.xaml |  24 +--
 .../HandyControl_Net_40/Themes/Theme.xaml     | 204 +++++++++---------
 .../Styles/Base/CheckComboBoxBaseStyle.xaml   | 180 ++++++++--------
 .../Themes/Styles/Base/ComboBoxBaseStyle.xaml |  24 +--
 .../HandyControl_Shared/Themes/Theme.xaml     | 204 +++++++++---------
 6 files changed, 388 insertions(+), 428 deletions(-)

diff --git a/src/Net_40/HandyControl_Net_40/Themes/Styles/Base/CheckComboBoxBaseStyle.xaml b/src/Net_40/HandyControl_Net_40/Themes/Styles/Base/CheckComboBoxBaseStyle.xaml
index 15a9927e..55458778 100644
--- a/src/Net_40/HandyControl_Net_40/Themes/Styles/Base/CheckComboBoxBaseStyle.xaml
+++ b/src/Net_40/HandyControl_Net_40/Themes/Styles/Base/CheckComboBoxBaseStyle.xaml
@@ -74,21 +74,23 @@
             </Grid.ColumnDefinitions>
             <Popup x:Name="PART_Popup" PlacementTarget="{Binding ElementName=toggleButton}" StaysOpen="False" IsOpen="{Binding IsDropDownOpen,RelativeSource={RelativeSource TemplatedParent},Mode=TwoWay}" AllowsTransparency="true" Grid.ColumnSpan="2" PopupAnimation="{StaticResource {x:Static SystemParameters.ComboBoxPopupAnimationKey}}" Placement="Bottom">
                 <Border CornerRadius="{Binding Path=(hc:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
-                    <Grid Margin="0,4" ClipToBounds="False">
-                        <Grid.RowDefinitions>
-                            <RowDefinition Height="Auto"/>
-                            <RowDefinition/>
-                        </Grid.RowDefinitions>
-                        <hc:CheckComboBoxItem x:Name="PART_SelectAll"  Style="{TemplateBinding ItemContainerStyle}" IsEnabled="{TemplateBinding ShowSelectAllButton}" Visibility="{Binding ShowSelectAllButton,RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}" HorizontalContentAlignment="Stretch" Content="{ex:Lang Key={x:Static langs:LangKeys.All}}"/>
-                        <ScrollViewer x:Name="DropDownScrollViewer" Grid.Row="1">
-                            <hc:SimplePanel RenderOptions.ClearTypeHint="Enabled">
-                                <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
-                                    <Rectangle x:Name="opaqueRect" Fill="{Binding Background, ElementName=dropDownBorder}" Height="{Binding ActualHeight, ElementName=dropDownBorder}" Width="{Binding ActualWidth, ElementName=dropDownBorder}"/>
-                                </Canvas>
-                                <ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
-                            </hc:SimplePanel>
-                        </ScrollViewer>
-                    </Grid>
+                    <hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
+                        <hc:ToggleBlock.CheckedContent>
+                            <Grid Margin="0,4" ClipToBounds="False">
+                                <Grid.RowDefinitions>
+                                    <RowDefinition Height="Auto"/>
+                                    <RowDefinition/>
+                                </Grid.RowDefinitions>
+                                <hc:CheckComboBoxItem x:Name="PART_SelectAll"  Style="{TemplateBinding ItemContainerStyle}" IsEnabled="{TemplateBinding ShowSelectAllButton}" Visibility="{Binding ShowSelectAllButton,RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}" HorizontalContentAlignment="Stretch" Content="{ex:Lang Key={x:Static langs:LangKeys.All}}"/>
+                                <ScrollViewer x:Name="DropDownScrollViewer" Grid.Row="1">
+                                    <ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
+                                </ScrollViewer>
+                            </Grid>
+                        </hc:ToggleBlock.CheckedContent>
+                        <hc:ToggleBlock.UnCheckedContent>
+                            <hc:Empty/>
+                        </hc:ToggleBlock.UnCheckedContent>
+                    </hc:ToggleBlock>
                 </Border>
             </Popup>
             <ToggleButton Grid.Column="0" x:Name="toggleButton" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="{TemplateBinding Background}" Grid.ColumnSpan="2" IsChecked="{Binding IsDropDownOpen,RelativeSource={RelativeSource TemplatedParent},Mode=TwoWay}" Style="{StaticResource ComboBoxToggleButton}"/>
@@ -104,10 +106,6 @@
                 <Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
                 <Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
             </Trigger>
-            <Trigger Property="ScrollViewer.CanContentScroll" SourceName="DropDownScrollViewer" Value="false">
-                <Setter Property="Canvas.Top" TargetName="opaqueRect" Value="{Binding VerticalOffset, ElementName=DropDownScrollViewer}"/>
-                <Setter Property="Canvas.Left" TargetName="opaqueRect" Value="{Binding HorizontalOffset, ElementName=DropDownScrollViewer}"/>
-            </Trigger>
             <MultiTrigger>
                 <MultiTrigger.Conditions>
                     <Condition Property="IsMouseOver" Value="true" SourceName="toggleButton"/>
@@ -165,21 +163,23 @@
             </StackPanel>
             <Popup x:Name="PART_Popup" Grid.Row="1" Grid.Column="0" PlacementTarget="{Binding ElementName=toggleButton}" AllowsTransparency="true" Grid.ColumnSpan="2" StaysOpen="False" IsOpen="{Binding IsDropDownOpen,RelativeSource={RelativeSource TemplatedParent},Mode=TwoWay}" Margin="1" PopupAnimation="{StaticResource {x:Static SystemParameters.ComboBoxPopupAnimationKey}}" Placement="Bottom">
                 <Border CornerRadius="{Binding Path=(hc:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
-                    <Grid Margin="0,4" ClipToBounds="False">
-                        <Grid.RowDefinitions>
-                            <RowDefinition Height="Auto"/>
-                            <RowDefinition/>
-                        </Grid.RowDefinitions>
-                        <hc:CheckComboBoxItem x:Name="PART_SelectAll"  Style="{TemplateBinding ItemContainerStyle}" IsEnabled="{TemplateBinding ShowSelectAllButton}" Visibility="{Binding ShowSelectAllButton,RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}" HorizontalContentAlignment="Stretch" Content="{ex:Lang Key={x:Static langs:LangKeys.All}}"/>
-                        <ScrollViewer x:Name="DropDownScrollViewer" Grid.Row="1">
-                            <hc:SimplePanel RenderOptions.ClearTypeHint="Enabled">
-                                <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
-                                    <Rectangle x:Name="opaqueRect" Fill="{Binding Background, ElementName=dropDownBorder}" Height="{Binding ActualHeight, ElementName=dropDownBorder}" Width="{Binding ActualWidth, ElementName=dropDownBorder}"/>
-                                </Canvas>
-                                <ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
-                            </hc:SimplePanel>
-                        </ScrollViewer>
-                    </Grid>
+                    <hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
+                        <hc:ToggleBlock.CheckedContent>
+                            <Grid Margin="0,4" ClipToBounds="False">
+                                <Grid.RowDefinitions>
+                                    <RowDefinition Height="Auto"/>
+                                    <RowDefinition/>
+                                </Grid.RowDefinitions>
+                                <hc:CheckComboBoxItem x:Name="PART_SelectAll"  Style="{TemplateBinding ItemContainerStyle}" IsEnabled="{TemplateBinding ShowSelectAllButton}" Visibility="{Binding ShowSelectAllButton,RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}" HorizontalContentAlignment="Stretch" Content="{ex:Lang Key={x:Static langs:LangKeys.All}}"/>
+                                <ScrollViewer x:Name="DropDownScrollViewer" Grid.Row="1">
+                                    <ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
+                                </ScrollViewer>
+                            </Grid>
+                        </hc:ToggleBlock.CheckedContent>
+                        <hc:ToggleBlock.UnCheckedContent>
+                            <hc:Empty/>
+                        </hc:ToggleBlock.UnCheckedContent>
+                    </hc:ToggleBlock>
                 </Border>
             </Popup>
             <ToggleButton Grid.Row="1" VerticalContentAlignment="{TemplateBinding VerticalContentAlignment}" HorizontalContentAlignment="{TemplateBinding HorizontalContentAlignment}" Padding="{TemplateBinding Padding}" Content="{Binding Path=(hc:InfoElement.Placeholder),RelativeSource={RelativeSource TemplatedParent}}" Grid.Column="0" x:Name="toggleButton" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="{TemplateBinding Background}" Grid.ColumnSpan="2" IsChecked="{Binding IsDropDownOpen, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}" Style="{StaticResource ComboBoxWatermarkToggleButton}"/>
@@ -195,10 +195,6 @@
                 <Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
                 <Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
             </Trigger>
-            <Trigger Property="ScrollViewer.CanContentScroll" SourceName="DropDownScrollViewer" Value="false">
-                <Setter Property="Canvas.Top" TargetName="opaqueRect" Value="{Binding VerticalOffset, ElementName=DropDownScrollViewer}"/>
-                <Setter Property="Canvas.Left" TargetName="opaqueRect" Value="{Binding HorizontalOffset, ElementName=DropDownScrollViewer}"/>
-            </Trigger>
             <MultiTrigger>
                 <MultiTrigger.Conditions>
                     <Condition Property="IsMouseOver" Value="true" SourceName="toggleButton"/>
@@ -232,21 +228,23 @@
             </StackPanel>
             <Popup Grid.Column="1" x:Name="PART_Popup" PlacementTarget="{Binding ElementName=toggleButton}" AllowsTransparency="true" Grid.ColumnSpan="2" StaysOpen="False" IsOpen="{Binding IsDropDownOpen, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}" Margin="1" PopupAnimation="{StaticResource {x:Static SystemParameters.ComboBoxPopupAnimationKey}}" Placement="Bottom">
                 <Border CornerRadius="{Binding Path=(hc:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
-                    <Grid Margin="0,4" ClipToBounds="False">
-                        <Grid.RowDefinitions>
-                            <RowDefinition Height="Auto"/>
-                            <RowDefinition/>
-                        </Grid.RowDefinitions>
-                        <hc:CheckComboBoxItem x:Name="PART_SelectAll"  Style="{TemplateBinding ItemContainerStyle}" IsEnabled="{TemplateBinding ShowSelectAllButton}" Visibility="{Binding ShowSelectAllButton,RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}" HorizontalContentAlignment="Stretch" Content="{ex:Lang Key={x:Static langs:LangKeys.All}}"/>
-                        <ScrollViewer x:Name="DropDownScrollViewer" Grid.Row="1">
-                            <hc:SimplePanel RenderOptions.ClearTypeHint="Enabled">
-                                <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
-                                    <Rectangle x:Name="opaqueRect" Fill="{Binding Background, ElementName=dropDownBorder}" Height="{Binding ActualHeight, ElementName=dropDownBorder}" Width="{Binding ActualWidth, ElementName=dropDownBorder}"/>
-                                </Canvas>
-                                <ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
-                            </hc:SimplePanel>
-                        </ScrollViewer>
-                    </Grid>
+                    <hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
+                        <hc:ToggleBlock.CheckedContent>
+                            <Grid Margin="0,4" ClipToBounds="False">
+                                <Grid.RowDefinitions>
+                                    <RowDefinition Height="Auto"/>
+                                    <RowDefinition/>
+                                </Grid.RowDefinitions>
+                                <hc:CheckComboBoxItem x:Name="PART_SelectAll"  Style="{TemplateBinding ItemContainerStyle}" IsEnabled="{TemplateBinding ShowSelectAllButton}" Visibility="{Binding ShowSelectAllButton,RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}" HorizontalContentAlignment="Stretch" Content="{ex:Lang Key={x:Static langs:LangKeys.All}}"/>
+                                <ScrollViewer x:Name="DropDownScrollViewer" Grid.Row="1">
+                                    <ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
+                                </ScrollViewer>
+                            </Grid>
+                        </hc:ToggleBlock.CheckedContent>
+                        <hc:ToggleBlock.UnCheckedContent>
+                            <hc:Empty/>
+                        </hc:ToggleBlock.UnCheckedContent>
+                    </hc:ToggleBlock>
                 </Border>
             </Popup>
             <ToggleButton Grid.Column="1" VerticalContentAlignment="{TemplateBinding VerticalContentAlignment}" HorizontalContentAlignment="{TemplateBinding HorizontalContentAlignment}" Padding="{TemplateBinding Padding}" Content="{Binding Path=(hc:InfoElement.Placeholder),RelativeSource={RelativeSource TemplatedParent}}" x:Name="toggleButton" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="{TemplateBinding Background}" Grid.ColumnSpan="2" IsChecked="{Binding IsDropDownOpen, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}" Style="{StaticResource ComboBoxWatermarkToggleButton}"/>
@@ -262,10 +260,6 @@
                 <Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
                 <Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
             </Trigger>
-            <Trigger Property="ScrollViewer.CanContentScroll" SourceName="DropDownScrollViewer" Value="false">
-                <Setter Property="Canvas.Top" TargetName="opaqueRect" Value="{Binding VerticalOffset, ElementName=DropDownScrollViewer}"/>
-                <Setter Property="Canvas.Left" TargetName="opaqueRect" Value="{Binding HorizontalOffset, ElementName=DropDownScrollViewer}"/>
-            </Trigger>
             <MultiTrigger>
                 <MultiTrigger.Conditions>
                     <Condition Property="IsMouseOver" Value="true" SourceName="toggleButton"/>
@@ -323,21 +317,23 @@
             </StackPanel>
             <Popup Grid.Row="1" Grid.Column="0" x:Name="PART_Popup" PlacementTarget="{Binding ElementName=toggleButton}" AllowsTransparency="true" Grid.ColumnSpan="2" StaysOpen="False" IsOpen="{Binding IsDropDownOpen, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}" Margin="1" PopupAnimation="{StaticResource {x:Static SystemParameters.ComboBoxPopupAnimationKey}}" Placement="Bottom">
                 <Border CornerRadius="{Binding Path=(hc:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
-                    <Grid Margin="0,4" ClipToBounds="False">
-                        <Grid.RowDefinitions>
-                            <RowDefinition Height="Auto"/>
-                            <RowDefinition/>
-                        </Grid.RowDefinitions>
-                        <hc:CheckComboBoxItem x:Name="PART_SelectAll"  Style="{TemplateBinding ItemContainerStyle}" IsEnabled="{TemplateBinding ShowSelectAllButton}" Visibility="{Binding ShowSelectAllButton,RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}" HorizontalContentAlignment="Stretch" Content="{ex:Lang Key={x:Static langs:LangKeys.All}}"/>
-                        <ScrollViewer x:Name="DropDownScrollViewer" Grid.Row="1">
-                            <hc:SimplePanel RenderOptions.ClearTypeHint="Enabled">
-                                <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
-                                    <Rectangle x:Name="opaqueRect" Fill="{Binding Background, ElementName=dropDownBorder}" Height="{Binding ActualHeight, ElementName=dropDownBorder}" Width="{Binding ActualWidth, ElementName=dropDownBorder}"/>
-                                </Canvas>
-                                <ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
-                            </hc:SimplePanel>
-                        </ScrollViewer>
-                    </Grid>
+                    <hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
+                        <hc:ToggleBlock.CheckedContent>
+                            <Grid Margin="0,4" ClipToBounds="False">
+                                <Grid.RowDefinitions>
+                                    <RowDefinition Height="Auto"/>
+                                    <RowDefinition/>
+                                </Grid.RowDefinitions>
+                                <hc:CheckComboBoxItem x:Name="PART_SelectAll"  Style="{TemplateBinding ItemContainerStyle}" IsEnabled="{TemplateBinding ShowSelectAllButton}" Visibility="{Binding ShowSelectAllButton,RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}" HorizontalContentAlignment="Stretch" Content="{ex:Lang Key={x:Static langs:LangKeys.All}}"/>
+                                <ScrollViewer x:Name="DropDownScrollViewer" Grid.Row="1">
+                                    <ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
+                                </ScrollViewer>
+                            </Grid>
+                        </hc:ToggleBlock.CheckedContent>
+                        <hc:ToggleBlock.UnCheckedContent>
+                            <hc:Empty/>
+                        </hc:ToggleBlock.UnCheckedContent>
+                    </hc:ToggleBlock>
                 </Border>
             </Popup>
             <TextBlock Grid.Column="0" Grid.ColumnSpan="2" FontSize="12" Text="{TemplateBinding ErrorStr}" Name="TextBlockError" VerticalAlignment="Bottom" Margin="9,0,0,4" Foreground="{DynamicResource DangerBrush}" Grid.Row="1"/>
@@ -355,10 +351,6 @@
                 <Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
                 <Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
             </Trigger>
-            <Trigger Property="ScrollViewer.CanContentScroll" SourceName="DropDownScrollViewer" Value="false">
-                <Setter Property="Canvas.Top" TargetName="opaqueRect" Value="{Binding VerticalOffset, ElementName=DropDownScrollViewer}"/>
-                <Setter Property="Canvas.Left" TargetName="opaqueRect" Value="{Binding HorizontalOffset, ElementName=DropDownScrollViewer}"/>
-            </Trigger>
             <MultiTrigger>
                 <MultiTrigger.Conditions>
                     <Condition Property="IsMouseOver" Value="true" SourceName="toggleButton"/>
@@ -430,21 +422,23 @@
             </StackPanel>
             <Popup Grid.Column="1" x:Name="PART_Popup" PlacementTarget="{Binding ElementName=toggleButton}" AllowsTransparency="true" Grid.ColumnSpan="2" StaysOpen="False" IsOpen="{Binding IsDropDownOpen, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}" Margin="1" PopupAnimation="{StaticResource {x:Static SystemParameters.ComboBoxPopupAnimationKey}}" Placement="Bottom">
                 <Border CornerRadius="{Binding Path=(hc:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
-                    <Grid Margin="0,4" ClipToBounds="False">
-                        <Grid.RowDefinitions>
-                            <RowDefinition Height="Auto"/>
-                            <RowDefinition/>
-                        </Grid.RowDefinitions>
-                        <hc:CheckComboBoxItem x:Name="PART_SelectAll"  Style="{TemplateBinding ItemContainerStyle}" IsEnabled="{TemplateBinding ShowSelectAllButton}" Visibility="{Binding ShowSelectAllButton,RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}" HorizontalContentAlignment="Stretch" Content="{ex:Lang Key={x:Static langs:LangKeys.All}}"/>
-                        <ScrollViewer x:Name="DropDownScrollViewer" Grid.Row="1">
-                            <hc:SimplePanel RenderOptions.ClearTypeHint="Enabled">
-                                <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
-                                    <Rectangle x:Name="opaqueRect" Fill="{Binding Background, ElementName=dropDownBorder}" Height="{Binding ActualHeight, ElementName=dropDownBorder}" Width="{Binding ActualWidth, ElementName=dropDownBorder}"/>
-                                </Canvas>
-                                <ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
-                            </hc:SimplePanel>
-                        </ScrollViewer>
-                    </Grid>
+                    <hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
+                        <hc:ToggleBlock.CheckedContent>
+                            <Grid Margin="0,4" ClipToBounds="False">
+                                <Grid.RowDefinitions>
+                                    <RowDefinition Height="Auto"/>
+                                    <RowDefinition/>
+                                </Grid.RowDefinitions>
+                                <hc:CheckComboBoxItem x:Name="PART_SelectAll"  Style="{TemplateBinding ItemContainerStyle}" IsEnabled="{TemplateBinding ShowSelectAllButton}" Visibility="{Binding ShowSelectAllButton,RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}" HorizontalContentAlignment="Stretch" Content="{ex:Lang Key={x:Static langs:LangKeys.All}}"/>
+                                <ScrollViewer x:Name="DropDownScrollViewer" Grid.Row="1">
+                                    <ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
+                                </ScrollViewer>
+                            </Grid>
+                        </hc:ToggleBlock.CheckedContent>
+                        <hc:ToggleBlock.UnCheckedContent>
+                            <hc:Empty/>
+                        </hc:ToggleBlock.UnCheckedContent>
+                    </hc:ToggleBlock>
                 </Border>
             </Popup>
             <TextBlock Grid.Column="1" Grid.ColumnSpan="2" FontSize="12" Text="{TemplateBinding ErrorStr}" Name="TextBlockError" VerticalAlignment="Bottom" Margin="9,0,0,4" Foreground="{DynamicResource DangerBrush}"/>
@@ -462,10 +456,6 @@
                 <Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
                 <Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
             </Trigger>
-            <Trigger Property="ScrollViewer.CanContentScroll" SourceName="DropDownScrollViewer" Value="false">
-                <Setter Property="Canvas.Top" TargetName="opaqueRect" Value="{Binding VerticalOffset, ElementName=DropDownScrollViewer}"/>
-                <Setter Property="Canvas.Left" TargetName="opaqueRect" Value="{Binding HorizontalOffset, ElementName=DropDownScrollViewer}"/>
-            </Trigger>
             <MultiTrigger>
                 <MultiTrigger.Conditions>
                     <Condition Property="IsMouseOver" Value="true" SourceName="toggleButton"/>
diff --git a/src/Net_40/HandyControl_Net_40/Themes/Styles/Base/ComboBoxBaseStyle.xaml b/src/Net_40/HandyControl_Net_40/Themes/Styles/Base/ComboBoxBaseStyle.xaml
index e64263e5..805422ab 100644
--- a/src/Net_40/HandyControl_Net_40/Themes/Styles/Base/ComboBoxBaseStyle.xaml
+++ b/src/Net_40/HandyControl_Net_40/Themes/Styles/Base/ComboBoxBaseStyle.xaml
@@ -85,7 +85,7 @@
                     <hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
                         <hc:ToggleBlock.CheckedContent>
                             <ScrollViewer Margin="0,4">
-                                <ItemsPresenter KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
+                                <ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
                             </ScrollViewer>
                         </hc:ToggleBlock.CheckedContent>
                         <hc:ToggleBlock.UnCheckedContent>
@@ -150,7 +150,7 @@
                     <hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
                         <hc:ToggleBlock.CheckedContent>
                             <ScrollViewer Margin="0,4">
-                                <ItemsPresenter KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
+                                <ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
                             </ScrollViewer>
                         </hc:ToggleBlock.CheckedContent>
                         <hc:ToggleBlock.UnCheckedContent>
@@ -213,7 +213,7 @@
                     <hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
                         <hc:ToggleBlock.CheckedContent>
                             <ScrollViewer Margin="0,4">
-                                <ItemsPresenter KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
+                                <ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
                             </ScrollViewer>
                         </hc:ToggleBlock.CheckedContent>
                         <hc:ToggleBlock.UnCheckedContent>
@@ -290,7 +290,7 @@
                     <hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
                         <hc:ToggleBlock.CheckedContent>
                             <ScrollViewer Margin="0,4">
-                                <ItemsPresenter KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
+                                <ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
                             </ScrollViewer>
                         </hc:ToggleBlock.CheckedContent>
                         <hc:ToggleBlock.UnCheckedContent>
@@ -355,7 +355,7 @@
                     <hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
                         <hc:ToggleBlock.CheckedContent>
                             <ScrollViewer Margin="0,4">
-                                <ItemsPresenter KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
+                                <ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
                             </ScrollViewer>
                         </hc:ToggleBlock.CheckedContent>
                         <hc:ToggleBlock.UnCheckedContent>
@@ -418,7 +418,7 @@
                     <hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
                         <hc:ToggleBlock.CheckedContent>
                             <ScrollViewer Margin="0,4">
-                                <ItemsPresenter KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
+                                <ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
                             </ScrollViewer>
                         </hc:ToggleBlock.CheckedContent>
                         <hc:ToggleBlock.UnCheckedContent>
@@ -590,7 +590,7 @@
                     <hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
                         <hc:ToggleBlock.CheckedContent>
                             <ScrollViewer Margin="0,4">
-                                <ItemsPresenter KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
+                                <ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
                             </ScrollViewer>
                         </hc:ToggleBlock.CheckedContent>
                         <hc:ToggleBlock.UnCheckedContent>
@@ -693,7 +693,7 @@
                     <hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
                         <hc:ToggleBlock.CheckedContent>
                             <ScrollViewer Margin="0,4">
-                                <ItemsPresenter KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
+                                <ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
                             </ScrollViewer>
                         </hc:ToggleBlock.CheckedContent>
                         <hc:ToggleBlock.UnCheckedContent>
@@ -799,7 +799,7 @@
                     <hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
                         <hc:ToggleBlock.CheckedContent>
                             <ScrollViewer Margin="0,4">
-                                <ItemsPresenter KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
+                                <ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
                             </ScrollViewer>
                         </hc:ToggleBlock.CheckedContent>
                         <hc:ToggleBlock.UnCheckedContent>
@@ -922,7 +922,7 @@
                     <hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
                         <hc:ToggleBlock.CheckedContent>
                             <ScrollViewer Margin="0,4">
-                                <ItemsPresenter KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
+                                <ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
                             </ScrollViewer>
                         </hc:ToggleBlock.CheckedContent>
                         <hc:ToggleBlock.UnCheckedContent>
@@ -1062,7 +1062,7 @@
                     <hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
                         <hc:ToggleBlock.CheckedContent>
                             <ScrollViewer Margin="0,4">
-                                <ItemsPresenter KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
+                                <ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
                             </ScrollViewer>
                         </hc:ToggleBlock.CheckedContent>
                         <hc:ToggleBlock.UnCheckedContent>
@@ -1182,7 +1182,7 @@
                     <hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
                         <hc:ToggleBlock.CheckedContent>
                             <ScrollViewer Margin="0,4">
-                                <ItemsPresenter KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
+                                <ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
                             </ScrollViewer>
                         </hc:ToggleBlock.CheckedContent>
                         <hc:ToggleBlock.UnCheckedContent>
diff --git a/src/Net_40/HandyControl_Net_40/Themes/Theme.xaml b/src/Net_40/HandyControl_Net_40/Themes/Theme.xaml
index 31109d94..41ae9f10 100644
--- a/src/Net_40/HandyControl_Net_40/Themes/Theme.xaml
+++ b/src/Net_40/HandyControl_Net_40/Themes/Theme.xaml
@@ -4517,7 +4517,7 @@
 					<hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
 						<hc:ToggleBlock.CheckedContent>
 							<ScrollViewer Margin="0,4">
-								<ItemsPresenter KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
+								<ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
 							</ScrollViewer>
 						</hc:ToggleBlock.CheckedContent>
 						<hc:ToggleBlock.UnCheckedContent>
@@ -4580,7 +4580,7 @@
 					<hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
 						<hc:ToggleBlock.CheckedContent>
 							<ScrollViewer Margin="0,4">
-								<ItemsPresenter KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
+								<ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
 							</ScrollViewer>
 						</hc:ToggleBlock.CheckedContent>
 						<hc:ToggleBlock.UnCheckedContent>
@@ -4641,7 +4641,7 @@
 					<hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
 						<hc:ToggleBlock.CheckedContent>
 							<ScrollViewer Margin="0,4">
-								<ItemsPresenter KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
+								<ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
 							</ScrollViewer>
 						</hc:ToggleBlock.CheckedContent>
 						<hc:ToggleBlock.UnCheckedContent>
@@ -4714,7 +4714,7 @@
 					<hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
 						<hc:ToggleBlock.CheckedContent>
 							<ScrollViewer Margin="0,4">
-								<ItemsPresenter KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
+								<ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
 							</ScrollViewer>
 						</hc:ToggleBlock.CheckedContent>
 						<hc:ToggleBlock.UnCheckedContent>
@@ -4777,7 +4777,7 @@
 					<hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
 						<hc:ToggleBlock.CheckedContent>
 							<ScrollViewer Margin="0,4">
-								<ItemsPresenter KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
+								<ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
 							</ScrollViewer>
 						</hc:ToggleBlock.CheckedContent>
 						<hc:ToggleBlock.UnCheckedContent>
@@ -4838,7 +4838,7 @@
 					<hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
 						<hc:ToggleBlock.CheckedContent>
 							<ScrollViewer Margin="0,4">
-								<ItemsPresenter KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
+								<ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
 							</ScrollViewer>
 						</hc:ToggleBlock.CheckedContent>
 						<hc:ToggleBlock.UnCheckedContent>
@@ -5002,7 +5002,7 @@
 					<hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
 						<hc:ToggleBlock.CheckedContent>
 							<ScrollViewer Margin="0,4">
-								<ItemsPresenter KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
+								<ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
 							</ScrollViewer>
 						</hc:ToggleBlock.CheckedContent>
 						<hc:ToggleBlock.UnCheckedContent>
@@ -5103,7 +5103,7 @@
 					<hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
 						<hc:ToggleBlock.CheckedContent>
 							<ScrollViewer Margin="0,4">
-								<ItemsPresenter KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
+								<ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
 							</ScrollViewer>
 						</hc:ToggleBlock.CheckedContent>
 						<hc:ToggleBlock.UnCheckedContent>
@@ -5207,7 +5207,7 @@
 					<hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
 						<hc:ToggleBlock.CheckedContent>
 							<ScrollViewer Margin="0,4">
-								<ItemsPresenter KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
+								<ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
 							</ScrollViewer>
 						</hc:ToggleBlock.CheckedContent>
 						<hc:ToggleBlock.UnCheckedContent>
@@ -5329,7 +5329,7 @@
 					<hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
 						<hc:ToggleBlock.CheckedContent>
 							<ScrollViewer Margin="0,4">
-								<ItemsPresenter KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
+								<ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
 							</ScrollViewer>
 						</hc:ToggleBlock.CheckedContent>
 						<hc:ToggleBlock.UnCheckedContent>
@@ -5467,7 +5467,7 @@
 					<hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
 						<hc:ToggleBlock.CheckedContent>
 							<ScrollViewer Margin="0,4">
-								<ItemsPresenter KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
+								<ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
 							</ScrollViewer>
 						</hc:ToggleBlock.CheckedContent>
 						<hc:ToggleBlock.UnCheckedContent>
@@ -5586,7 +5586,7 @@
 					<hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
 						<hc:ToggleBlock.CheckedContent>
 							<ScrollViewer Margin="0,4">
-								<ItemsPresenter KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
+								<ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
 							</ScrollViewer>
 						</hc:ToggleBlock.CheckedContent>
 						<hc:ToggleBlock.UnCheckedContent>
@@ -6764,21 +6764,23 @@
 			</Grid.ColumnDefinitions>
 			<Popup x:Name="PART_Popup" PlacementTarget="{Binding ElementName=toggleButton}" StaysOpen="False" IsOpen="{Binding IsDropDownOpen,RelativeSource={RelativeSource TemplatedParent},Mode=TwoWay}" AllowsTransparency="true" Grid.ColumnSpan="2" PopupAnimation="{StaticResource {x:Static SystemParameters.ComboBoxPopupAnimationKey}}" Placement="Bottom">
 				<Border CornerRadius="{Binding Path=(hc:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
-					<Grid Margin="0,4" ClipToBounds="False">
-						<Grid.RowDefinitions>
-							<RowDefinition Height="Auto" />
-							<RowDefinition />
-						</Grid.RowDefinitions>
-						<hc:CheckComboBoxItem x:Name="PART_SelectAll" Style="{TemplateBinding ItemContainerStyle}" IsEnabled="{TemplateBinding ShowSelectAllButton}" Visibility="{Binding ShowSelectAllButton,RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}" HorizontalContentAlignment="Stretch" Content="{ex:Lang Key={x:Static langs:LangKeys.All}}" />
-						<ScrollViewer x:Name="DropDownScrollViewer" Grid.Row="1">
-							<hc:SimplePanel RenderOptions.ClearTypeHint="Enabled">
-								<Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
-									<Rectangle x:Name="opaqueRect" Fill="{Binding Background, ElementName=dropDownBorder}" Height="{Binding ActualHeight, ElementName=dropDownBorder}" Width="{Binding ActualWidth, ElementName=dropDownBorder}" />
-								</Canvas>
-								<ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
-							</hc:SimplePanel>
-						</ScrollViewer>
-					</Grid>
+					<hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
+						<hc:ToggleBlock.CheckedContent>
+							<Grid Margin="0,4" ClipToBounds="False">
+								<Grid.RowDefinitions>
+									<RowDefinition Height="Auto" />
+									<RowDefinition />
+								</Grid.RowDefinitions>
+								<hc:CheckComboBoxItem x:Name="PART_SelectAll" Style="{TemplateBinding ItemContainerStyle}" IsEnabled="{TemplateBinding ShowSelectAllButton}" Visibility="{Binding ShowSelectAllButton,RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}" HorizontalContentAlignment="Stretch" Content="{ex:Lang Key={x:Static langs:LangKeys.All}}" />
+								<ScrollViewer x:Name="DropDownScrollViewer" Grid.Row="1">
+									<ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
+								</ScrollViewer>
+							</Grid>
+						</hc:ToggleBlock.CheckedContent>
+						<hc:ToggleBlock.UnCheckedContent>
+							<hc:Empty />
+						</hc:ToggleBlock.UnCheckedContent>
+					</hc:ToggleBlock>
 				</Border>
 			</Popup>
 			<ToggleButton Grid.Column="0" x:Name="toggleButton" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="{TemplateBinding Background}" Grid.ColumnSpan="2" IsChecked="{Binding IsDropDownOpen,RelativeSource={RelativeSource TemplatedParent},Mode=TwoWay}" Style="{StaticResource ComboBoxToggleButton}" />
@@ -6794,10 +6796,6 @@
 				<Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}" />
 				<Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}" />
 			</Trigger>
-			<Trigger Property="ScrollViewer.CanContentScroll" SourceName="DropDownScrollViewer" Value="false">
-				<Setter Property="Canvas.Top" TargetName="opaqueRect" Value="{Binding VerticalOffset, ElementName=DropDownScrollViewer}" />
-				<Setter Property="Canvas.Left" TargetName="opaqueRect" Value="{Binding HorizontalOffset, ElementName=DropDownScrollViewer}" />
-			</Trigger>
 			<MultiTrigger>
 				<MultiTrigger.Conditions>
 					<Condition Property="IsMouseOver" Value="true" SourceName="toggleButton" />
@@ -6853,21 +6851,23 @@
 			</StackPanel>
 			<Popup x:Name="PART_Popup" Grid.Row="1" Grid.Column="0" PlacementTarget="{Binding ElementName=toggleButton}" AllowsTransparency="true" Grid.ColumnSpan="2" StaysOpen="False" IsOpen="{Binding IsDropDownOpen,RelativeSource={RelativeSource TemplatedParent},Mode=TwoWay}" Margin="1" PopupAnimation="{StaticResource {x:Static SystemParameters.ComboBoxPopupAnimationKey}}" Placement="Bottom">
 				<Border CornerRadius="{Binding Path=(hc:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
-					<Grid Margin="0,4" ClipToBounds="False">
-						<Grid.RowDefinitions>
-							<RowDefinition Height="Auto" />
-							<RowDefinition />
-						</Grid.RowDefinitions>
-						<hc:CheckComboBoxItem x:Name="PART_SelectAll" Style="{TemplateBinding ItemContainerStyle}" IsEnabled="{TemplateBinding ShowSelectAllButton}" Visibility="{Binding ShowSelectAllButton,RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}" HorizontalContentAlignment="Stretch" Content="{ex:Lang Key={x:Static langs:LangKeys.All}}" />
-						<ScrollViewer x:Name="DropDownScrollViewer" Grid.Row="1">
-							<hc:SimplePanel RenderOptions.ClearTypeHint="Enabled">
-								<Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
-									<Rectangle x:Name="opaqueRect" Fill="{Binding Background, ElementName=dropDownBorder}" Height="{Binding ActualHeight, ElementName=dropDownBorder}" Width="{Binding ActualWidth, ElementName=dropDownBorder}" />
-								</Canvas>
-								<ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
-							</hc:SimplePanel>
-						</ScrollViewer>
-					</Grid>
+					<hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
+						<hc:ToggleBlock.CheckedContent>
+							<Grid Margin="0,4" ClipToBounds="False">
+								<Grid.RowDefinitions>
+									<RowDefinition Height="Auto" />
+									<RowDefinition />
+								</Grid.RowDefinitions>
+								<hc:CheckComboBoxItem x:Name="PART_SelectAll" Style="{TemplateBinding ItemContainerStyle}" IsEnabled="{TemplateBinding ShowSelectAllButton}" Visibility="{Binding ShowSelectAllButton,RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}" HorizontalContentAlignment="Stretch" Content="{ex:Lang Key={x:Static langs:LangKeys.All}}" />
+								<ScrollViewer x:Name="DropDownScrollViewer" Grid.Row="1">
+									<ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
+								</ScrollViewer>
+							</Grid>
+						</hc:ToggleBlock.CheckedContent>
+						<hc:ToggleBlock.UnCheckedContent>
+							<hc:Empty />
+						</hc:ToggleBlock.UnCheckedContent>
+					</hc:ToggleBlock>
 				</Border>
 			</Popup>
 			<ToggleButton Grid.Row="1" VerticalContentAlignment="{TemplateBinding VerticalContentAlignment}" HorizontalContentAlignment="{TemplateBinding HorizontalContentAlignment}" Padding="{TemplateBinding Padding}" Content="{Binding Path=(hc:InfoElement.Placeholder),RelativeSource={RelativeSource TemplatedParent}}" Grid.Column="0" x:Name="toggleButton" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="{TemplateBinding Background}" Grid.ColumnSpan="2" IsChecked="{Binding IsDropDownOpen, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}" Style="{StaticResource ComboBoxWatermarkToggleButton}" />
@@ -6883,10 +6883,6 @@
 				<Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}" />
 				<Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}" />
 			</Trigger>
-			<Trigger Property="ScrollViewer.CanContentScroll" SourceName="DropDownScrollViewer" Value="false">
-				<Setter Property="Canvas.Top" TargetName="opaqueRect" Value="{Binding VerticalOffset, ElementName=DropDownScrollViewer}" />
-				<Setter Property="Canvas.Left" TargetName="opaqueRect" Value="{Binding HorizontalOffset, ElementName=DropDownScrollViewer}" />
-			</Trigger>
 			<MultiTrigger>
 				<MultiTrigger.Conditions>
 					<Condition Property="IsMouseOver" Value="true" SourceName="toggleButton" />
@@ -6919,21 +6915,23 @@
 			</StackPanel>
 			<Popup Grid.Column="1" x:Name="PART_Popup" PlacementTarget="{Binding ElementName=toggleButton}" AllowsTransparency="true" Grid.ColumnSpan="2" StaysOpen="False" IsOpen="{Binding IsDropDownOpen, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}" Margin="1" PopupAnimation="{StaticResource {x:Static SystemParameters.ComboBoxPopupAnimationKey}}" Placement="Bottom">
 				<Border CornerRadius="{Binding Path=(hc:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
-					<Grid Margin="0,4" ClipToBounds="False">
-						<Grid.RowDefinitions>
-							<RowDefinition Height="Auto" />
-							<RowDefinition />
-						</Grid.RowDefinitions>
-						<hc:CheckComboBoxItem x:Name="PART_SelectAll" Style="{TemplateBinding ItemContainerStyle}" IsEnabled="{TemplateBinding ShowSelectAllButton}" Visibility="{Binding ShowSelectAllButton,RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}" HorizontalContentAlignment="Stretch" Content="{ex:Lang Key={x:Static langs:LangKeys.All}}" />
-						<ScrollViewer x:Name="DropDownScrollViewer" Grid.Row="1">
-							<hc:SimplePanel RenderOptions.ClearTypeHint="Enabled">
-								<Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
-									<Rectangle x:Name="opaqueRect" Fill="{Binding Background, ElementName=dropDownBorder}" Height="{Binding ActualHeight, ElementName=dropDownBorder}" Width="{Binding ActualWidth, ElementName=dropDownBorder}" />
-								</Canvas>
-								<ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
-							</hc:SimplePanel>
-						</ScrollViewer>
-					</Grid>
+					<hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
+						<hc:ToggleBlock.CheckedContent>
+							<Grid Margin="0,4" ClipToBounds="False">
+								<Grid.RowDefinitions>
+									<RowDefinition Height="Auto" />
+									<RowDefinition />
+								</Grid.RowDefinitions>
+								<hc:CheckComboBoxItem x:Name="PART_SelectAll" Style="{TemplateBinding ItemContainerStyle}" IsEnabled="{TemplateBinding ShowSelectAllButton}" Visibility="{Binding ShowSelectAllButton,RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}" HorizontalContentAlignment="Stretch" Content="{ex:Lang Key={x:Static langs:LangKeys.All}}" />
+								<ScrollViewer x:Name="DropDownScrollViewer" Grid.Row="1">
+									<ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
+								</ScrollViewer>
+							</Grid>
+						</hc:ToggleBlock.CheckedContent>
+						<hc:ToggleBlock.UnCheckedContent>
+							<hc:Empty />
+						</hc:ToggleBlock.UnCheckedContent>
+					</hc:ToggleBlock>
 				</Border>
 			</Popup>
 			<ToggleButton Grid.Column="1" VerticalContentAlignment="{TemplateBinding VerticalContentAlignment}" HorizontalContentAlignment="{TemplateBinding HorizontalContentAlignment}" Padding="{TemplateBinding Padding}" Content="{Binding Path=(hc:InfoElement.Placeholder),RelativeSource={RelativeSource TemplatedParent}}" x:Name="toggleButton" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="{TemplateBinding Background}" Grid.ColumnSpan="2" IsChecked="{Binding IsDropDownOpen, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}" Style="{StaticResource ComboBoxWatermarkToggleButton}" />
@@ -6949,10 +6947,6 @@
 				<Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}" />
 				<Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}" />
 			</Trigger>
-			<Trigger Property="ScrollViewer.CanContentScroll" SourceName="DropDownScrollViewer" Value="false">
-				<Setter Property="Canvas.Top" TargetName="opaqueRect" Value="{Binding VerticalOffset, ElementName=DropDownScrollViewer}" />
-				<Setter Property="Canvas.Left" TargetName="opaqueRect" Value="{Binding HorizontalOffset, ElementName=DropDownScrollViewer}" />
-			</Trigger>
 			<MultiTrigger>
 				<MultiTrigger.Conditions>
 					<Condition Property="IsMouseOver" Value="true" SourceName="toggleButton" />
@@ -7008,21 +7002,23 @@
 			</StackPanel>
 			<Popup Grid.Row="1" Grid.Column="0" x:Name="PART_Popup" PlacementTarget="{Binding ElementName=toggleButton}" AllowsTransparency="true" Grid.ColumnSpan="2" StaysOpen="False" IsOpen="{Binding IsDropDownOpen, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}" Margin="1" PopupAnimation="{StaticResource {x:Static SystemParameters.ComboBoxPopupAnimationKey}}" Placement="Bottom">
 				<Border CornerRadius="{Binding Path=(hc:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
-					<Grid Margin="0,4" ClipToBounds="False">
-						<Grid.RowDefinitions>
-							<RowDefinition Height="Auto" />
-							<RowDefinition />
-						</Grid.RowDefinitions>
-						<hc:CheckComboBoxItem x:Name="PART_SelectAll" Style="{TemplateBinding ItemContainerStyle}" IsEnabled="{TemplateBinding ShowSelectAllButton}" Visibility="{Binding ShowSelectAllButton,RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}" HorizontalContentAlignment="Stretch" Content="{ex:Lang Key={x:Static langs:LangKeys.All}}" />
-						<ScrollViewer x:Name="DropDownScrollViewer" Grid.Row="1">
-							<hc:SimplePanel RenderOptions.ClearTypeHint="Enabled">
-								<Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
-									<Rectangle x:Name="opaqueRect" Fill="{Binding Background, ElementName=dropDownBorder}" Height="{Binding ActualHeight, ElementName=dropDownBorder}" Width="{Binding ActualWidth, ElementName=dropDownBorder}" />
-								</Canvas>
-								<ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
-							</hc:SimplePanel>
-						</ScrollViewer>
-					</Grid>
+					<hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
+						<hc:ToggleBlock.CheckedContent>
+							<Grid Margin="0,4" ClipToBounds="False">
+								<Grid.RowDefinitions>
+									<RowDefinition Height="Auto" />
+									<RowDefinition />
+								</Grid.RowDefinitions>
+								<hc:CheckComboBoxItem x:Name="PART_SelectAll" Style="{TemplateBinding ItemContainerStyle}" IsEnabled="{TemplateBinding ShowSelectAllButton}" Visibility="{Binding ShowSelectAllButton,RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}" HorizontalContentAlignment="Stretch" Content="{ex:Lang Key={x:Static langs:LangKeys.All}}" />
+								<ScrollViewer x:Name="DropDownScrollViewer" Grid.Row="1">
+									<ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
+								</ScrollViewer>
+							</Grid>
+						</hc:ToggleBlock.CheckedContent>
+						<hc:ToggleBlock.UnCheckedContent>
+							<hc:Empty />
+						</hc:ToggleBlock.UnCheckedContent>
+					</hc:ToggleBlock>
 				</Border>
 			</Popup>
 			<TextBlock Grid.Column="0" Grid.ColumnSpan="2" FontSize="12" Text="{TemplateBinding ErrorStr}" Name="TextBlockError" VerticalAlignment="Bottom" Margin="9,0,0,4" Foreground="{DynamicResource DangerBrush}" Grid.Row="1" />
@@ -7040,10 +7036,6 @@
 				<Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}" />
 				<Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}" />
 			</Trigger>
-			<Trigger Property="ScrollViewer.CanContentScroll" SourceName="DropDownScrollViewer" Value="false">
-				<Setter Property="Canvas.Top" TargetName="opaqueRect" Value="{Binding VerticalOffset, ElementName=DropDownScrollViewer}" />
-				<Setter Property="Canvas.Left" TargetName="opaqueRect" Value="{Binding HorizontalOffset, ElementName=DropDownScrollViewer}" />
-			</Trigger>
 			<MultiTrigger>
 				<MultiTrigger.Conditions>
 					<Condition Property="IsMouseOver" Value="true" SourceName="toggleButton" />
@@ -7114,21 +7106,23 @@
 			</StackPanel>
 			<Popup Grid.Column="1" x:Name="PART_Popup" PlacementTarget="{Binding ElementName=toggleButton}" AllowsTransparency="true" Grid.ColumnSpan="2" StaysOpen="False" IsOpen="{Binding IsDropDownOpen, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}" Margin="1" PopupAnimation="{StaticResource {x:Static SystemParameters.ComboBoxPopupAnimationKey}}" Placement="Bottom">
 				<Border CornerRadius="{Binding Path=(hc:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
-					<Grid Margin="0,4" ClipToBounds="False">
-						<Grid.RowDefinitions>
-							<RowDefinition Height="Auto" />
-							<RowDefinition />
-						</Grid.RowDefinitions>
-						<hc:CheckComboBoxItem x:Name="PART_SelectAll" Style="{TemplateBinding ItemContainerStyle}" IsEnabled="{TemplateBinding ShowSelectAllButton}" Visibility="{Binding ShowSelectAllButton,RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}" HorizontalContentAlignment="Stretch" Content="{ex:Lang Key={x:Static langs:LangKeys.All}}" />
-						<ScrollViewer x:Name="DropDownScrollViewer" Grid.Row="1">
-							<hc:SimplePanel RenderOptions.ClearTypeHint="Enabled">
-								<Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
-									<Rectangle x:Name="opaqueRect" Fill="{Binding Background, ElementName=dropDownBorder}" Height="{Binding ActualHeight, ElementName=dropDownBorder}" Width="{Binding ActualWidth, ElementName=dropDownBorder}" />
-								</Canvas>
-								<ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
-							</hc:SimplePanel>
-						</ScrollViewer>
-					</Grid>
+					<hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
+						<hc:ToggleBlock.CheckedContent>
+							<Grid Margin="0,4" ClipToBounds="False">
+								<Grid.RowDefinitions>
+									<RowDefinition Height="Auto" />
+									<RowDefinition />
+								</Grid.RowDefinitions>
+								<hc:CheckComboBoxItem x:Name="PART_SelectAll" Style="{TemplateBinding ItemContainerStyle}" IsEnabled="{TemplateBinding ShowSelectAllButton}" Visibility="{Binding ShowSelectAllButton,RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}" HorizontalContentAlignment="Stretch" Content="{ex:Lang Key={x:Static langs:LangKeys.All}}" />
+								<ScrollViewer x:Name="DropDownScrollViewer" Grid.Row="1">
+									<ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
+								</ScrollViewer>
+							</Grid>
+						</hc:ToggleBlock.CheckedContent>
+						<hc:ToggleBlock.UnCheckedContent>
+							<hc:Empty />
+						</hc:ToggleBlock.UnCheckedContent>
+					</hc:ToggleBlock>
 				</Border>
 			</Popup>
 			<TextBlock Grid.Column="1" Grid.ColumnSpan="2" FontSize="12" Text="{TemplateBinding ErrorStr}" Name="TextBlockError" VerticalAlignment="Bottom" Margin="9,0,0,4" Foreground="{DynamicResource DangerBrush}" />
@@ -7146,10 +7140,6 @@
 				<Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}" />
 				<Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}" />
 			</Trigger>
-			<Trigger Property="ScrollViewer.CanContentScroll" SourceName="DropDownScrollViewer" Value="false">
-				<Setter Property="Canvas.Top" TargetName="opaqueRect" Value="{Binding VerticalOffset, ElementName=DropDownScrollViewer}" />
-				<Setter Property="Canvas.Left" TargetName="opaqueRect" Value="{Binding HorizontalOffset, ElementName=DropDownScrollViewer}" />
-			</Trigger>
 			<MultiTrigger>
 				<MultiTrigger.Conditions>
 					<Condition Property="IsMouseOver" Value="true" SourceName="toggleButton" />
diff --git a/src/Shared/HandyControl_Shared/Themes/Styles/Base/CheckComboBoxBaseStyle.xaml b/src/Shared/HandyControl_Shared/Themes/Styles/Base/CheckComboBoxBaseStyle.xaml
index 1791e4d9..d54231ea 100644
--- a/src/Shared/HandyControl_Shared/Themes/Styles/Base/CheckComboBoxBaseStyle.xaml
+++ b/src/Shared/HandyControl_Shared/Themes/Styles/Base/CheckComboBoxBaseStyle.xaml
@@ -74,21 +74,23 @@
             </Grid.ColumnDefinitions>
             <Popup x:Name="PART_Popup" PlacementTarget="{Binding ElementName=toggleButton}" StaysOpen="False" IsOpen="{Binding IsDropDownOpen,RelativeSource={RelativeSource TemplatedParent},Mode=TwoWay}" AllowsTransparency="true" Grid.ColumnSpan="2" PopupAnimation="{StaticResource {x:Static SystemParameters.ComboBoxPopupAnimationKey}}" Placement="Bottom">
                 <Border CornerRadius="{Binding Path=(hc:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
-                    <Grid Margin="0,4" ClipToBounds="False">
-                        <Grid.RowDefinitions>
-                            <RowDefinition Height="Auto"/>
-                            <RowDefinition/>
-                        </Grid.RowDefinitions>
-                        <hc:CheckComboBoxItem x:Name="PART_SelectAll"  Style="{TemplateBinding ItemContainerStyle}" IsEnabled="{TemplateBinding ShowSelectAllButton}" Visibility="{Binding ShowSelectAllButton,RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}" HorizontalContentAlignment="Stretch" Content="{ex:Lang Key={x:Static langs:LangKeys.All}}"/>
-                        <ScrollViewer x:Name="DropDownScrollViewer" Grid.Row="1">
-                            <hc:SimplePanel RenderOptions.ClearTypeHint="Enabled">
-                                <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
-                                    <Rectangle x:Name="opaqueRect" Fill="{Binding Background, ElementName=dropDownBorder}" Height="{Binding ActualHeight, ElementName=dropDownBorder}" Width="{Binding ActualWidth, ElementName=dropDownBorder}"/>
-                                </Canvas>
-                                <ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
-                            </hc:SimplePanel>
-                        </ScrollViewer>
-                    </Grid>
+                    <hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
+                        <hc:ToggleBlock.CheckedContent>
+                            <Grid Margin="0,4" ClipToBounds="False">
+                                <Grid.RowDefinitions>
+                                    <RowDefinition Height="Auto"/>
+                                    <RowDefinition/>
+                                </Grid.RowDefinitions>
+                                <hc:CheckComboBoxItem x:Name="PART_SelectAll"  Style="{TemplateBinding ItemContainerStyle}" IsEnabled="{TemplateBinding ShowSelectAllButton}" Visibility="{Binding ShowSelectAllButton,RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}" HorizontalContentAlignment="Stretch" Content="{ex:Lang Key={x:Static langs:LangKeys.All}}"/>
+                                <ScrollViewer x:Name="DropDownScrollViewer" Grid.Row="1">
+                                    <ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
+                                </ScrollViewer>
+                            </Grid>
+                        </hc:ToggleBlock.CheckedContent>
+                        <hc:ToggleBlock.UnCheckedContent>
+                            <hc:Empty/>
+                        </hc:ToggleBlock.UnCheckedContent>
+                    </hc:ToggleBlock>
                 </Border>
             </Popup>
             <ToggleButton Grid.Column="0" x:Name="toggleButton" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="{TemplateBinding Background}" Grid.ColumnSpan="2" IsChecked="{Binding IsDropDownOpen,RelativeSource={RelativeSource TemplatedParent},Mode=TwoWay}" Style="{StaticResource ComboBoxToggleButton}"/>
@@ -111,10 +113,6 @@
                 </MultiTrigger.Conditions>
                 <Setter Property="ScrollViewer.CanContentScroll" Value="false"/>
             </MultiTrigger>
-            <Trigger Property="ScrollViewer.CanContentScroll" SourceName="DropDownScrollViewer" Value="false">
-                <Setter Property="Canvas.Top" TargetName="opaqueRect" Value="{Binding VerticalOffset, ElementName=DropDownScrollViewer}"/>
-                <Setter Property="Canvas.Left" TargetName="opaqueRect" Value="{Binding HorizontalOffset, ElementName=DropDownScrollViewer}"/>
-            </Trigger>
             <MultiTrigger>
                 <MultiTrigger.Conditions>
                     <Condition Property="IsMouseOver" Value="true" SourceName="toggleButton"/>
@@ -172,21 +170,23 @@
             </StackPanel>
             <Popup x:Name="PART_Popup" Grid.Row="1" Grid.Column="0" PlacementTarget="{Binding ElementName=toggleButton}" AllowsTransparency="true" Grid.ColumnSpan="2" StaysOpen="False" IsOpen="{Binding IsDropDownOpen,RelativeSource={RelativeSource TemplatedParent},Mode=TwoWay}" Margin="1" PopupAnimation="{StaticResource {x:Static SystemParameters.ComboBoxPopupAnimationKey}}" Placement="Bottom">
                 <Border CornerRadius="{Binding Path=(hc:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
-                    <Grid Margin="0,4" ClipToBounds="False">
-                        <Grid.RowDefinitions>
-                            <RowDefinition Height="Auto"/>
-                            <RowDefinition/>
-                        </Grid.RowDefinitions>
-                        <hc:CheckComboBoxItem x:Name="PART_SelectAll"  Style="{TemplateBinding ItemContainerStyle}" IsEnabled="{TemplateBinding ShowSelectAllButton}" Visibility="{Binding ShowSelectAllButton,RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}" HorizontalContentAlignment="Stretch" Content="{ex:Lang Key={x:Static langs:LangKeys.All}}"/>
-                        <ScrollViewer x:Name="DropDownScrollViewer" Grid.Row="1">
-                            <hc:SimplePanel RenderOptions.ClearTypeHint="Enabled">
-                                <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
-                                    <Rectangle x:Name="opaqueRect" Fill="{Binding Background, ElementName=dropDownBorder}" Height="{Binding ActualHeight, ElementName=dropDownBorder}" Width="{Binding ActualWidth, ElementName=dropDownBorder}"/>
-                                </Canvas>
-                                <ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
-                            </hc:SimplePanel>
-                        </ScrollViewer>
-                    </Grid>
+                    <hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
+                        <hc:ToggleBlock.CheckedContent>
+                            <Grid Margin="0,4" ClipToBounds="False">
+                                <Grid.RowDefinitions>
+                                    <RowDefinition Height="Auto"/>
+                                    <RowDefinition/>
+                                </Grid.RowDefinitions>
+                                <hc:CheckComboBoxItem x:Name="PART_SelectAll"  Style="{TemplateBinding ItemContainerStyle}" IsEnabled="{TemplateBinding ShowSelectAllButton}" Visibility="{Binding ShowSelectAllButton,RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}" HorizontalContentAlignment="Stretch" Content="{ex:Lang Key={x:Static langs:LangKeys.All}}"/>
+                                <ScrollViewer x:Name="DropDownScrollViewer" Grid.Row="1">
+                                    <ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
+                                </ScrollViewer>
+                            </Grid>
+                        </hc:ToggleBlock.CheckedContent>
+                        <hc:ToggleBlock.UnCheckedContent>
+                            <hc:Empty/>
+                        </hc:ToggleBlock.UnCheckedContent>
+                    </hc:ToggleBlock>
                 </Border>
             </Popup>
             <ToggleButton Grid.Row="1" VerticalContentAlignment="{TemplateBinding VerticalContentAlignment}" HorizontalContentAlignment="{TemplateBinding HorizontalContentAlignment}" Padding="{TemplateBinding Padding}" Content="{Binding Path=(hc:InfoElement.Placeholder),RelativeSource={RelativeSource TemplatedParent}}" Grid.Column="0" x:Name="toggleButton" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="{TemplateBinding Background}" Grid.ColumnSpan="2" IsChecked="{Binding IsDropDownOpen, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}" Style="{StaticResource ComboBoxWatermarkToggleButton}"/>
@@ -209,10 +209,6 @@
                 </MultiTrigger.Conditions>
                 <Setter Property="ScrollViewer.CanContentScroll" Value="false"/>
             </MultiTrigger>
-            <Trigger Property="ScrollViewer.CanContentScroll" SourceName="DropDownScrollViewer" Value="false">
-                <Setter Property="Canvas.Top" TargetName="opaqueRect" Value="{Binding VerticalOffset, ElementName=DropDownScrollViewer}"/>
-                <Setter Property="Canvas.Left" TargetName="opaqueRect" Value="{Binding HorizontalOffset, ElementName=DropDownScrollViewer}"/>
-            </Trigger>
             <MultiTrigger>
                 <MultiTrigger.Conditions>
                     <Condition Property="IsMouseOver" Value="true" SourceName="toggleButton"/>
@@ -246,21 +242,23 @@
             </StackPanel>
             <Popup Grid.Column="1" x:Name="PART_Popup" PlacementTarget="{Binding ElementName=toggleButton}" AllowsTransparency="true" Grid.ColumnSpan="2" StaysOpen="False" IsOpen="{Binding IsDropDownOpen, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}" Margin="1" PopupAnimation="{StaticResource {x:Static SystemParameters.ComboBoxPopupAnimationKey}}" Placement="Bottom">
                 <Border CornerRadius="{Binding Path=(hc:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
-                    <Grid Margin="0,4" ClipToBounds="False">
-                        <Grid.RowDefinitions>
-                            <RowDefinition Height="Auto"/>
-                            <RowDefinition/>
-                        </Grid.RowDefinitions>
-                        <hc:CheckComboBoxItem x:Name="PART_SelectAll"  Style="{TemplateBinding ItemContainerStyle}" IsEnabled="{TemplateBinding ShowSelectAllButton}" Visibility="{Binding ShowSelectAllButton,RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}" HorizontalContentAlignment="Stretch" Content="{ex:Lang Key={x:Static langs:LangKeys.All}}"/>
-                        <ScrollViewer x:Name="DropDownScrollViewer" Grid.Row="1">
-                            <hc:SimplePanel RenderOptions.ClearTypeHint="Enabled">
-                                <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
-                                    <Rectangle x:Name="opaqueRect" Fill="{Binding Background, ElementName=dropDownBorder}" Height="{Binding ActualHeight, ElementName=dropDownBorder}" Width="{Binding ActualWidth, ElementName=dropDownBorder}"/>
-                                </Canvas>
-                                <ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
-                            </hc:SimplePanel>
-                        </ScrollViewer>
-                    </Grid>
+                    <hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
+                        <hc:ToggleBlock.CheckedContent>
+                            <Grid Margin="0,4" ClipToBounds="False">
+                                <Grid.RowDefinitions>
+                                    <RowDefinition Height="Auto"/>
+                                    <RowDefinition/>
+                                </Grid.RowDefinitions>
+                                <hc:CheckComboBoxItem x:Name="PART_SelectAll"  Style="{TemplateBinding ItemContainerStyle}" IsEnabled="{TemplateBinding ShowSelectAllButton}" Visibility="{Binding ShowSelectAllButton,RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}" HorizontalContentAlignment="Stretch" Content="{ex:Lang Key={x:Static langs:LangKeys.All}}"/>
+                                <ScrollViewer x:Name="DropDownScrollViewer" Grid.Row="1">
+                                    <ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
+                                </ScrollViewer>
+                            </Grid>
+                        </hc:ToggleBlock.CheckedContent>
+                        <hc:ToggleBlock.UnCheckedContent>
+                            <hc:Empty/>
+                        </hc:ToggleBlock.UnCheckedContent>
+                    </hc:ToggleBlock>
                 </Border>
             </Popup>
             <ToggleButton Grid.Column="1" VerticalContentAlignment="{TemplateBinding VerticalContentAlignment}" HorizontalContentAlignment="{TemplateBinding HorizontalContentAlignment}" Padding="{TemplateBinding Padding}" Content="{Binding Path=(hc:InfoElement.Placeholder),RelativeSource={RelativeSource TemplatedParent}}" x:Name="toggleButton" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="{TemplateBinding Background}" Grid.ColumnSpan="2" IsChecked="{Binding IsDropDownOpen, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}" Style="{StaticResource ComboBoxWatermarkToggleButton}"/>
@@ -283,10 +281,6 @@
                 </MultiTrigger.Conditions>
                 <Setter Property="ScrollViewer.CanContentScroll" Value="false"/>
             </MultiTrigger>
-            <Trigger Property="ScrollViewer.CanContentScroll" SourceName="DropDownScrollViewer" Value="false">
-                <Setter Property="Canvas.Top" TargetName="opaqueRect" Value="{Binding VerticalOffset, ElementName=DropDownScrollViewer}"/>
-                <Setter Property="Canvas.Left" TargetName="opaqueRect" Value="{Binding HorizontalOffset, ElementName=DropDownScrollViewer}"/>
-            </Trigger>
             <MultiTrigger>
                 <MultiTrigger.Conditions>
                     <Condition Property="IsMouseOver" Value="true" SourceName="toggleButton"/>
@@ -344,21 +338,23 @@
             </StackPanel>
             <Popup Grid.Row="1" Grid.Column="0" x:Name="PART_Popup" PlacementTarget="{Binding ElementName=toggleButton}" AllowsTransparency="true" Grid.ColumnSpan="2" StaysOpen="False" IsOpen="{Binding IsDropDownOpen, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}" Margin="1" PopupAnimation="{StaticResource {x:Static SystemParameters.ComboBoxPopupAnimationKey}}" Placement="Bottom">
                 <Border CornerRadius="{Binding Path=(hc:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
-                    <Grid Margin="0,4" ClipToBounds="False">
-                        <Grid.RowDefinitions>
-                            <RowDefinition Height="Auto"/>
-                            <RowDefinition/>
-                        </Grid.RowDefinitions>
-                        <hc:CheckComboBoxItem x:Name="PART_SelectAll"  Style="{TemplateBinding ItemContainerStyle}" IsEnabled="{TemplateBinding ShowSelectAllButton}" Visibility="{Binding ShowSelectAllButton,RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}" HorizontalContentAlignment="Stretch" Content="{ex:Lang Key={x:Static langs:LangKeys.All}}"/>
-                        <ScrollViewer x:Name="DropDownScrollViewer" Grid.Row="1">
-                            <hc:SimplePanel RenderOptions.ClearTypeHint="Enabled">
-                                <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
-                                    <Rectangle x:Name="opaqueRect" Fill="{Binding Background, ElementName=dropDownBorder}" Height="{Binding ActualHeight, ElementName=dropDownBorder}" Width="{Binding ActualWidth, ElementName=dropDownBorder}"/>
-                                </Canvas>
-                                <ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
-                            </hc:SimplePanel>
-                        </ScrollViewer>
-                    </Grid>
+                    <hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
+                        <hc:ToggleBlock.CheckedContent>
+                            <Grid Margin="0,4" ClipToBounds="False">
+                                <Grid.RowDefinitions>
+                                    <RowDefinition Height="Auto"/>
+                                    <RowDefinition/>
+                                </Grid.RowDefinitions>
+                                <hc:CheckComboBoxItem x:Name="PART_SelectAll"  Style="{TemplateBinding ItemContainerStyle}" IsEnabled="{TemplateBinding ShowSelectAllButton}" Visibility="{Binding ShowSelectAllButton,RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}" HorizontalContentAlignment="Stretch" Content="{ex:Lang Key={x:Static langs:LangKeys.All}}"/>
+                                <ScrollViewer x:Name="DropDownScrollViewer" Grid.Row="1">
+                                    <ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
+                                </ScrollViewer>
+                            </Grid>
+                        </hc:ToggleBlock.CheckedContent>
+                        <hc:ToggleBlock.UnCheckedContent>
+                            <hc:Empty/>
+                        </hc:ToggleBlock.UnCheckedContent>
+                    </hc:ToggleBlock>
                 </Border>
             </Popup>
             <TextBlock Grid.Column="0" Grid.ColumnSpan="2" FontSize="12" Text="{TemplateBinding ErrorStr}" Name="TextBlockError" VerticalAlignment="Bottom" Margin="9,0,0,4" Foreground="{DynamicResource DangerBrush}" Grid.Row="1"/>
@@ -383,10 +379,6 @@
                 </MultiTrigger.Conditions>
                 <Setter Property="ScrollViewer.CanContentScroll" Value="false"/>
             </MultiTrigger>
-            <Trigger Property="ScrollViewer.CanContentScroll" SourceName="DropDownScrollViewer" Value="false">
-                <Setter Property="Canvas.Top" TargetName="opaqueRect" Value="{Binding VerticalOffset, ElementName=DropDownScrollViewer}"/>
-                <Setter Property="Canvas.Left" TargetName="opaqueRect" Value="{Binding HorizontalOffset, ElementName=DropDownScrollViewer}"/>
-            </Trigger>
             <MultiTrigger>
                 <MultiTrigger.Conditions>
                     <Condition Property="IsMouseOver" Value="true" SourceName="toggleButton"/>
@@ -458,21 +450,23 @@
             </StackPanel>
             <Popup Grid.Column="1" x:Name="PART_Popup" PlacementTarget="{Binding ElementName=toggleButton}" AllowsTransparency="true" Grid.ColumnSpan="2" StaysOpen="False" IsOpen="{Binding IsDropDownOpen, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}" Margin="1" PopupAnimation="{StaticResource {x:Static SystemParameters.ComboBoxPopupAnimationKey}}" Placement="Bottom">
                 <Border CornerRadius="{Binding Path=(hc:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
-                    <Grid Margin="0,4" ClipToBounds="False">
-                        <Grid.RowDefinitions>
-                            <RowDefinition Height="Auto"/>
-                            <RowDefinition/>
-                        </Grid.RowDefinitions>
-                        <hc:CheckComboBoxItem x:Name="PART_SelectAll"  Style="{TemplateBinding ItemContainerStyle}" IsEnabled="{TemplateBinding ShowSelectAllButton}" Visibility="{Binding ShowSelectAllButton,RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}" HorizontalContentAlignment="Stretch" Content="{ex:Lang Key={x:Static langs:LangKeys.All}}"/>
-                        <ScrollViewer x:Name="DropDownScrollViewer" Grid.Row="1">
-                            <hc:SimplePanel RenderOptions.ClearTypeHint="Enabled">
-                                <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
-                                    <Rectangle x:Name="opaqueRect" Fill="{Binding Background, ElementName=dropDownBorder}" Height="{Binding ActualHeight, ElementName=dropDownBorder}" Width="{Binding ActualWidth, ElementName=dropDownBorder}"/>
-                                </Canvas>
-                                <ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
-                            </hc:SimplePanel>
-                        </ScrollViewer>
-                    </Grid>
+                    <hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
+                        <hc:ToggleBlock.CheckedContent>
+                            <Grid Margin="0,4" ClipToBounds="False">
+                                <Grid.RowDefinitions>
+                                    <RowDefinition Height="Auto"/>
+                                    <RowDefinition/>
+                                </Grid.RowDefinitions>
+                                <hc:CheckComboBoxItem x:Name="PART_SelectAll"  Style="{TemplateBinding ItemContainerStyle}" IsEnabled="{TemplateBinding ShowSelectAllButton}" Visibility="{Binding ShowSelectAllButton,RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}" HorizontalContentAlignment="Stretch" Content="{ex:Lang Key={x:Static langs:LangKeys.All}}"/>
+                                <ScrollViewer x:Name="DropDownScrollViewer" Grid.Row="1">
+                                    <ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
+                                </ScrollViewer>
+                            </Grid>
+                        </hc:ToggleBlock.CheckedContent>
+                        <hc:ToggleBlock.UnCheckedContent>
+                            <hc:Empty/>
+                        </hc:ToggleBlock.UnCheckedContent>
+                    </hc:ToggleBlock>
                 </Border>
             </Popup>
             <TextBlock Grid.Column="1" Grid.ColumnSpan="2" FontSize="12" Text="{TemplateBinding ErrorStr}" Name="TextBlockError" VerticalAlignment="Bottom" Margin="9,0,0,4" Foreground="{DynamicResource DangerBrush}"/>
@@ -497,10 +491,6 @@
                 </MultiTrigger.Conditions>
                 <Setter Property="ScrollViewer.CanContentScroll" Value="false"/>
             </MultiTrigger>
-            <Trigger Property="ScrollViewer.CanContentScroll" SourceName="DropDownScrollViewer" Value="false">
-                <Setter Property="Canvas.Top" TargetName="opaqueRect" Value="{Binding VerticalOffset, ElementName=DropDownScrollViewer}"/>
-                <Setter Property="Canvas.Left" TargetName="opaqueRect" Value="{Binding HorizontalOffset, ElementName=DropDownScrollViewer}"/>
-            </Trigger>
             <MultiTrigger>
                 <MultiTrigger.Conditions>
                     <Condition Property="IsMouseOver" Value="true" SourceName="toggleButton"/>
diff --git a/src/Shared/HandyControl_Shared/Themes/Styles/Base/ComboBoxBaseStyle.xaml b/src/Shared/HandyControl_Shared/Themes/Styles/Base/ComboBoxBaseStyle.xaml
index 81a2d478..64b50da7 100644
--- a/src/Shared/HandyControl_Shared/Themes/Styles/Base/ComboBoxBaseStyle.xaml
+++ b/src/Shared/HandyControl_Shared/Themes/Styles/Base/ComboBoxBaseStyle.xaml
@@ -85,7 +85,7 @@
                     <hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
                         <hc:ToggleBlock.CheckedContent>
                             <ScrollViewer Margin="0,4">
-                                <ItemsPresenter KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
+                                <ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
                             </ScrollViewer>
                         </hc:ToggleBlock.CheckedContent>
                         <hc:ToggleBlock.UnCheckedContent>
@@ -157,7 +157,7 @@
                     <hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
                         <hc:ToggleBlock.CheckedContent>
                             <ScrollViewer Margin="0,4">
-                                <ItemsPresenter KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
+                                <ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
                             </ScrollViewer>
                         </hc:ToggleBlock.CheckedContent>
                         <hc:ToggleBlock.UnCheckedContent>
@@ -227,7 +227,7 @@
                     <hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
                         <hc:ToggleBlock.CheckedContent>
                             <ScrollViewer Margin="0,4">
-                                <ItemsPresenter KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
+                                <ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
                             </ScrollViewer>
                         </hc:ToggleBlock.CheckedContent>
                         <hc:ToggleBlock.UnCheckedContent>
@@ -311,7 +311,7 @@
                     <hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
                         <hc:ToggleBlock.CheckedContent>
                             <ScrollViewer Margin="0,4">
-                                <ItemsPresenter KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
+                                <ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
                             </ScrollViewer>
                         </hc:ToggleBlock.CheckedContent>
                         <hc:ToggleBlock.UnCheckedContent>
@@ -383,7 +383,7 @@
                     <hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
                         <hc:ToggleBlock.CheckedContent>
                             <ScrollViewer Margin="0,4">
-                                <ItemsPresenter KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
+                                <ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
                             </ScrollViewer>
                         </hc:ToggleBlock.CheckedContent>
                         <hc:ToggleBlock.UnCheckedContent>
@@ -453,7 +453,7 @@
                     <hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
                         <hc:ToggleBlock.CheckedContent>
                             <ScrollViewer Margin="0,4">
-                                <ItemsPresenter KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
+                                <ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
                             </ScrollViewer>
                         </hc:ToggleBlock.CheckedContent>
                         <hc:ToggleBlock.UnCheckedContent>
@@ -632,7 +632,7 @@
                     <hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
                         <hc:ToggleBlock.CheckedContent>
                             <ScrollViewer Margin="0,4">
-                                <ItemsPresenter KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
+                                <ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
                             </ScrollViewer>
                         </hc:ToggleBlock.CheckedContent>
                         <hc:ToggleBlock.UnCheckedContent>
@@ -742,7 +742,7 @@
                     <hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
                         <hc:ToggleBlock.CheckedContent>
                             <ScrollViewer Margin="0,4">
-                                <ItemsPresenter KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
+                                <ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
                             </ScrollViewer>
                         </hc:ToggleBlock.CheckedContent>
                         <hc:ToggleBlock.UnCheckedContent>
@@ -855,7 +855,7 @@
                     <hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
                         <hc:ToggleBlock.CheckedContent>
                             <ScrollViewer Margin="0,4">
-                                <ItemsPresenter KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
+                                <ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
                             </ScrollViewer>
                         </hc:ToggleBlock.CheckedContent>
                         <hc:ToggleBlock.UnCheckedContent>
@@ -985,7 +985,7 @@
                     <hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
                         <hc:ToggleBlock.CheckedContent>
                             <ScrollViewer Margin="0,4">
-                                <ItemsPresenter KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
+                                <ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
                             </ScrollViewer>
                         </hc:ToggleBlock.CheckedContent>
                         <hc:ToggleBlock.UnCheckedContent>
@@ -1132,7 +1132,7 @@
                     <hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
                         <hc:ToggleBlock.CheckedContent>
                             <ScrollViewer Margin="0,4">
-                                <ItemsPresenter KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
+                                <ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
                             </ScrollViewer>
                         </hc:ToggleBlock.CheckedContent>
                         <hc:ToggleBlock.UnCheckedContent>
@@ -1259,7 +1259,7 @@
                     <hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
                         <hc:ToggleBlock.CheckedContent>
                             <ScrollViewer Margin="0,4">
-                                <ItemsPresenter KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
+                                <ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
                             </ScrollViewer>
                         </hc:ToggleBlock.CheckedContent>
                         <hc:ToggleBlock.UnCheckedContent>
diff --git a/src/Shared/HandyControl_Shared/Themes/Theme.xaml b/src/Shared/HandyControl_Shared/Themes/Theme.xaml
index 43eacdfc..d47a8346 100644
--- a/src/Shared/HandyControl_Shared/Themes/Theme.xaml
+++ b/src/Shared/HandyControl_Shared/Themes/Theme.xaml
@@ -4516,7 +4516,7 @@
 					<hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
 						<hc:ToggleBlock.CheckedContent>
 							<ScrollViewer Margin="0,4">
-								<ItemsPresenter KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
+								<ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
 							</ScrollViewer>
 						</hc:ToggleBlock.CheckedContent>
 						<hc:ToggleBlock.UnCheckedContent>
@@ -4586,7 +4586,7 @@
 					<hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
 						<hc:ToggleBlock.CheckedContent>
 							<ScrollViewer Margin="0,4">
-								<ItemsPresenter KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
+								<ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
 							</ScrollViewer>
 						</hc:ToggleBlock.CheckedContent>
 						<hc:ToggleBlock.UnCheckedContent>
@@ -4654,7 +4654,7 @@
 					<hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
 						<hc:ToggleBlock.CheckedContent>
 							<ScrollViewer Margin="0,4">
-								<ItemsPresenter KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
+								<ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
 							</ScrollViewer>
 						</hc:ToggleBlock.CheckedContent>
 						<hc:ToggleBlock.UnCheckedContent>
@@ -4734,7 +4734,7 @@
 					<hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
 						<hc:ToggleBlock.CheckedContent>
 							<ScrollViewer Margin="0,4">
-								<ItemsPresenter KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
+								<ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
 							</ScrollViewer>
 						</hc:ToggleBlock.CheckedContent>
 						<hc:ToggleBlock.UnCheckedContent>
@@ -4804,7 +4804,7 @@
 					<hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
 						<hc:ToggleBlock.CheckedContent>
 							<ScrollViewer Margin="0,4">
-								<ItemsPresenter KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
+								<ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
 							</ScrollViewer>
 						</hc:ToggleBlock.CheckedContent>
 						<hc:ToggleBlock.UnCheckedContent>
@@ -4872,7 +4872,7 @@
 					<hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
 						<hc:ToggleBlock.CheckedContent>
 							<ScrollViewer Margin="0,4">
-								<ItemsPresenter KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
+								<ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
 							</ScrollViewer>
 						</hc:ToggleBlock.CheckedContent>
 						<hc:ToggleBlock.UnCheckedContent>
@@ -5043,7 +5043,7 @@
 					<hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
 						<hc:ToggleBlock.CheckedContent>
 							<ScrollViewer Margin="0,4">
-								<ItemsPresenter KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
+								<ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
 							</ScrollViewer>
 						</hc:ToggleBlock.CheckedContent>
 						<hc:ToggleBlock.UnCheckedContent>
@@ -5151,7 +5151,7 @@
 					<hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
 						<hc:ToggleBlock.CheckedContent>
 							<ScrollViewer Margin="0,4">
-								<ItemsPresenter KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
+								<ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
 							</ScrollViewer>
 						</hc:ToggleBlock.CheckedContent>
 						<hc:ToggleBlock.UnCheckedContent>
@@ -5262,7 +5262,7 @@
 					<hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
 						<hc:ToggleBlock.CheckedContent>
 							<ScrollViewer Margin="0,4">
-								<ItemsPresenter KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
+								<ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
 							</ScrollViewer>
 						</hc:ToggleBlock.CheckedContent>
 						<hc:ToggleBlock.UnCheckedContent>
@@ -5391,7 +5391,7 @@
 					<hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
 						<hc:ToggleBlock.CheckedContent>
 							<ScrollViewer Margin="0,4">
-								<ItemsPresenter KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
+								<ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
 							</ScrollViewer>
 						</hc:ToggleBlock.CheckedContent>
 						<hc:ToggleBlock.UnCheckedContent>
@@ -5536,7 +5536,7 @@
 					<hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
 						<hc:ToggleBlock.CheckedContent>
 							<ScrollViewer Margin="0,4">
-								<ItemsPresenter KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
+								<ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
 							</ScrollViewer>
 						</hc:ToggleBlock.CheckedContent>
 						<hc:ToggleBlock.UnCheckedContent>
@@ -5662,7 +5662,7 @@
 					<hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
 						<hc:ToggleBlock.CheckedContent>
 							<ScrollViewer Margin="0,4">
-								<ItemsPresenter KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
+								<ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
 							</ScrollViewer>
 						</hc:ToggleBlock.CheckedContent>
 						<hc:ToggleBlock.UnCheckedContent>
@@ -6847,21 +6847,23 @@
 			</Grid.ColumnDefinitions>
 			<Popup x:Name="PART_Popup" PlacementTarget="{Binding ElementName=toggleButton}" StaysOpen="False" IsOpen="{Binding IsDropDownOpen,RelativeSource={RelativeSource TemplatedParent},Mode=TwoWay}" AllowsTransparency="true" Grid.ColumnSpan="2" PopupAnimation="{StaticResource {x:Static SystemParameters.ComboBoxPopupAnimationKey}}" Placement="Bottom">
 				<Border CornerRadius="{Binding Path=(hc:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
-					<Grid Margin="0,4" ClipToBounds="False">
-						<Grid.RowDefinitions>
-							<RowDefinition Height="Auto" />
-							<RowDefinition />
-						</Grid.RowDefinitions>
-						<hc:CheckComboBoxItem x:Name="PART_SelectAll" Style="{TemplateBinding ItemContainerStyle}" IsEnabled="{TemplateBinding ShowSelectAllButton}" Visibility="{Binding ShowSelectAllButton,RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}" HorizontalContentAlignment="Stretch" Content="{ex:Lang Key={x:Static langs:LangKeys.All}}" />
-						<ScrollViewer x:Name="DropDownScrollViewer" Grid.Row="1">
-							<hc:SimplePanel RenderOptions.ClearTypeHint="Enabled">
-								<Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
-									<Rectangle x:Name="opaqueRect" Fill="{Binding Background, ElementName=dropDownBorder}" Height="{Binding ActualHeight, ElementName=dropDownBorder}" Width="{Binding ActualWidth, ElementName=dropDownBorder}" />
-								</Canvas>
-								<ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
-							</hc:SimplePanel>
-						</ScrollViewer>
-					</Grid>
+					<hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
+						<hc:ToggleBlock.CheckedContent>
+							<Grid Margin="0,4" ClipToBounds="False">
+								<Grid.RowDefinitions>
+									<RowDefinition Height="Auto" />
+									<RowDefinition />
+								</Grid.RowDefinitions>
+								<hc:CheckComboBoxItem x:Name="PART_SelectAll" Style="{TemplateBinding ItemContainerStyle}" IsEnabled="{TemplateBinding ShowSelectAllButton}" Visibility="{Binding ShowSelectAllButton,RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}" HorizontalContentAlignment="Stretch" Content="{ex:Lang Key={x:Static langs:LangKeys.All}}" />
+								<ScrollViewer x:Name="DropDownScrollViewer" Grid.Row="1">
+									<ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
+								</ScrollViewer>
+							</Grid>
+						</hc:ToggleBlock.CheckedContent>
+						<hc:ToggleBlock.UnCheckedContent>
+							<hc:Empty />
+						</hc:ToggleBlock.UnCheckedContent>
+					</hc:ToggleBlock>
 				</Border>
 			</Popup>
 			<ToggleButton Grid.Column="0" x:Name="toggleButton" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="{TemplateBinding Background}" Grid.ColumnSpan="2" IsChecked="{Binding IsDropDownOpen,RelativeSource={RelativeSource TemplatedParent},Mode=TwoWay}" Style="{StaticResource ComboBoxToggleButton}" />
@@ -6884,10 +6886,6 @@
 				</MultiTrigger.Conditions>
 				<Setter Property="ScrollViewer.CanContentScroll" Value="false" />
 			</MultiTrigger>
-			<Trigger Property="ScrollViewer.CanContentScroll" SourceName="DropDownScrollViewer" Value="false">
-				<Setter Property="Canvas.Top" TargetName="opaqueRect" Value="{Binding VerticalOffset, ElementName=DropDownScrollViewer}" />
-				<Setter Property="Canvas.Left" TargetName="opaqueRect" Value="{Binding HorizontalOffset, ElementName=DropDownScrollViewer}" />
-			</Trigger>
 			<MultiTrigger>
 				<MultiTrigger.Conditions>
 					<Condition Property="IsMouseOver" Value="true" SourceName="toggleButton" />
@@ -6943,21 +6941,23 @@
 			</StackPanel>
 			<Popup x:Name="PART_Popup" Grid.Row="1" Grid.Column="0" PlacementTarget="{Binding ElementName=toggleButton}" AllowsTransparency="true" Grid.ColumnSpan="2" StaysOpen="False" IsOpen="{Binding IsDropDownOpen,RelativeSource={RelativeSource TemplatedParent},Mode=TwoWay}" Margin="1" PopupAnimation="{StaticResource {x:Static SystemParameters.ComboBoxPopupAnimationKey}}" Placement="Bottom">
 				<Border CornerRadius="{Binding Path=(hc:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
-					<Grid Margin="0,4" ClipToBounds="False">
-						<Grid.RowDefinitions>
-							<RowDefinition Height="Auto" />
-							<RowDefinition />
-						</Grid.RowDefinitions>
-						<hc:CheckComboBoxItem x:Name="PART_SelectAll" Style="{TemplateBinding ItemContainerStyle}" IsEnabled="{TemplateBinding ShowSelectAllButton}" Visibility="{Binding ShowSelectAllButton,RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}" HorizontalContentAlignment="Stretch" Content="{ex:Lang Key={x:Static langs:LangKeys.All}}" />
-						<ScrollViewer x:Name="DropDownScrollViewer" Grid.Row="1">
-							<hc:SimplePanel RenderOptions.ClearTypeHint="Enabled">
-								<Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
-									<Rectangle x:Name="opaqueRect" Fill="{Binding Background, ElementName=dropDownBorder}" Height="{Binding ActualHeight, ElementName=dropDownBorder}" Width="{Binding ActualWidth, ElementName=dropDownBorder}" />
-								</Canvas>
-								<ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
-							</hc:SimplePanel>
-						</ScrollViewer>
-					</Grid>
+					<hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
+						<hc:ToggleBlock.CheckedContent>
+							<Grid Margin="0,4" ClipToBounds="False">
+								<Grid.RowDefinitions>
+									<RowDefinition Height="Auto" />
+									<RowDefinition />
+								</Grid.RowDefinitions>
+								<hc:CheckComboBoxItem x:Name="PART_SelectAll" Style="{TemplateBinding ItemContainerStyle}" IsEnabled="{TemplateBinding ShowSelectAllButton}" Visibility="{Binding ShowSelectAllButton,RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}" HorizontalContentAlignment="Stretch" Content="{ex:Lang Key={x:Static langs:LangKeys.All}}" />
+								<ScrollViewer x:Name="DropDownScrollViewer" Grid.Row="1">
+									<ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
+								</ScrollViewer>
+							</Grid>
+						</hc:ToggleBlock.CheckedContent>
+						<hc:ToggleBlock.UnCheckedContent>
+							<hc:Empty />
+						</hc:ToggleBlock.UnCheckedContent>
+					</hc:ToggleBlock>
 				</Border>
 			</Popup>
 			<ToggleButton Grid.Row="1" VerticalContentAlignment="{TemplateBinding VerticalContentAlignment}" HorizontalContentAlignment="{TemplateBinding HorizontalContentAlignment}" Padding="{TemplateBinding Padding}" Content="{Binding Path=(hc:InfoElement.Placeholder),RelativeSource={RelativeSource TemplatedParent}}" Grid.Column="0" x:Name="toggleButton" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="{TemplateBinding Background}" Grid.ColumnSpan="2" IsChecked="{Binding IsDropDownOpen, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}" Style="{StaticResource ComboBoxWatermarkToggleButton}" />
@@ -6980,10 +6980,6 @@
 				</MultiTrigger.Conditions>
 				<Setter Property="ScrollViewer.CanContentScroll" Value="false" />
 			</MultiTrigger>
-			<Trigger Property="ScrollViewer.CanContentScroll" SourceName="DropDownScrollViewer" Value="false">
-				<Setter Property="Canvas.Top" TargetName="opaqueRect" Value="{Binding VerticalOffset, ElementName=DropDownScrollViewer}" />
-				<Setter Property="Canvas.Left" TargetName="opaqueRect" Value="{Binding HorizontalOffset, ElementName=DropDownScrollViewer}" />
-			</Trigger>
 			<MultiTrigger>
 				<MultiTrigger.Conditions>
 					<Condition Property="IsMouseOver" Value="true" SourceName="toggleButton" />
@@ -7016,21 +7012,23 @@
 			</StackPanel>
 			<Popup Grid.Column="1" x:Name="PART_Popup" PlacementTarget="{Binding ElementName=toggleButton}" AllowsTransparency="true" Grid.ColumnSpan="2" StaysOpen="False" IsOpen="{Binding IsDropDownOpen, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}" Margin="1" PopupAnimation="{StaticResource {x:Static SystemParameters.ComboBoxPopupAnimationKey}}" Placement="Bottom">
 				<Border CornerRadius="{Binding Path=(hc:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
-					<Grid Margin="0,4" ClipToBounds="False">
-						<Grid.RowDefinitions>
-							<RowDefinition Height="Auto" />
-							<RowDefinition />
-						</Grid.RowDefinitions>
-						<hc:CheckComboBoxItem x:Name="PART_SelectAll" Style="{TemplateBinding ItemContainerStyle}" IsEnabled="{TemplateBinding ShowSelectAllButton}" Visibility="{Binding ShowSelectAllButton,RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}" HorizontalContentAlignment="Stretch" Content="{ex:Lang Key={x:Static langs:LangKeys.All}}" />
-						<ScrollViewer x:Name="DropDownScrollViewer" Grid.Row="1">
-							<hc:SimplePanel RenderOptions.ClearTypeHint="Enabled">
-								<Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
-									<Rectangle x:Name="opaqueRect" Fill="{Binding Background, ElementName=dropDownBorder}" Height="{Binding ActualHeight, ElementName=dropDownBorder}" Width="{Binding ActualWidth, ElementName=dropDownBorder}" />
-								</Canvas>
-								<ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
-							</hc:SimplePanel>
-						</ScrollViewer>
-					</Grid>
+					<hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
+						<hc:ToggleBlock.CheckedContent>
+							<Grid Margin="0,4" ClipToBounds="False">
+								<Grid.RowDefinitions>
+									<RowDefinition Height="Auto" />
+									<RowDefinition />
+								</Grid.RowDefinitions>
+								<hc:CheckComboBoxItem x:Name="PART_SelectAll" Style="{TemplateBinding ItemContainerStyle}" IsEnabled="{TemplateBinding ShowSelectAllButton}" Visibility="{Binding ShowSelectAllButton,RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}" HorizontalContentAlignment="Stretch" Content="{ex:Lang Key={x:Static langs:LangKeys.All}}" />
+								<ScrollViewer x:Name="DropDownScrollViewer" Grid.Row="1">
+									<ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
+								</ScrollViewer>
+							</Grid>
+						</hc:ToggleBlock.CheckedContent>
+						<hc:ToggleBlock.UnCheckedContent>
+							<hc:Empty />
+						</hc:ToggleBlock.UnCheckedContent>
+					</hc:ToggleBlock>
 				</Border>
 			</Popup>
 			<ToggleButton Grid.Column="1" VerticalContentAlignment="{TemplateBinding VerticalContentAlignment}" HorizontalContentAlignment="{TemplateBinding HorizontalContentAlignment}" Padding="{TemplateBinding Padding}" Content="{Binding Path=(hc:InfoElement.Placeholder),RelativeSource={RelativeSource TemplatedParent}}" x:Name="toggleButton" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="{TemplateBinding Background}" Grid.ColumnSpan="2" IsChecked="{Binding IsDropDownOpen, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}" Style="{StaticResource ComboBoxWatermarkToggleButton}" />
@@ -7053,10 +7051,6 @@
 				</MultiTrigger.Conditions>
 				<Setter Property="ScrollViewer.CanContentScroll" Value="false" />
 			</MultiTrigger>
-			<Trigger Property="ScrollViewer.CanContentScroll" SourceName="DropDownScrollViewer" Value="false">
-				<Setter Property="Canvas.Top" TargetName="opaqueRect" Value="{Binding VerticalOffset, ElementName=DropDownScrollViewer}" />
-				<Setter Property="Canvas.Left" TargetName="opaqueRect" Value="{Binding HorizontalOffset, ElementName=DropDownScrollViewer}" />
-			</Trigger>
 			<MultiTrigger>
 				<MultiTrigger.Conditions>
 					<Condition Property="IsMouseOver" Value="true" SourceName="toggleButton" />
@@ -7112,21 +7106,23 @@
 			</StackPanel>
 			<Popup Grid.Row="1" Grid.Column="0" x:Name="PART_Popup" PlacementTarget="{Binding ElementName=toggleButton}" AllowsTransparency="true" Grid.ColumnSpan="2" StaysOpen="False" IsOpen="{Binding IsDropDownOpen, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}" Margin="1" PopupAnimation="{StaticResource {x:Static SystemParameters.ComboBoxPopupAnimationKey}}" Placement="Bottom">
 				<Border CornerRadius="{Binding Path=(hc:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
-					<Grid Margin="0,4" ClipToBounds="False">
-						<Grid.RowDefinitions>
-							<RowDefinition Height="Auto" />
-							<RowDefinition />
-						</Grid.RowDefinitions>
-						<hc:CheckComboBoxItem x:Name="PART_SelectAll" Style="{TemplateBinding ItemContainerStyle}" IsEnabled="{TemplateBinding ShowSelectAllButton}" Visibility="{Binding ShowSelectAllButton,RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}" HorizontalContentAlignment="Stretch" Content="{ex:Lang Key={x:Static langs:LangKeys.All}}" />
-						<ScrollViewer x:Name="DropDownScrollViewer" Grid.Row="1">
-							<hc:SimplePanel RenderOptions.ClearTypeHint="Enabled">
-								<Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
-									<Rectangle x:Name="opaqueRect" Fill="{Binding Background, ElementName=dropDownBorder}" Height="{Binding ActualHeight, ElementName=dropDownBorder}" Width="{Binding ActualWidth, ElementName=dropDownBorder}" />
-								</Canvas>
-								<ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
-							</hc:SimplePanel>
-						</ScrollViewer>
-					</Grid>
+					<hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
+						<hc:ToggleBlock.CheckedContent>
+							<Grid Margin="0,4" ClipToBounds="False">
+								<Grid.RowDefinitions>
+									<RowDefinition Height="Auto" />
+									<RowDefinition />
+								</Grid.RowDefinitions>
+								<hc:CheckComboBoxItem x:Name="PART_SelectAll" Style="{TemplateBinding ItemContainerStyle}" IsEnabled="{TemplateBinding ShowSelectAllButton}" Visibility="{Binding ShowSelectAllButton,RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}" HorizontalContentAlignment="Stretch" Content="{ex:Lang Key={x:Static langs:LangKeys.All}}" />
+								<ScrollViewer x:Name="DropDownScrollViewer" Grid.Row="1">
+									<ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
+								</ScrollViewer>
+							</Grid>
+						</hc:ToggleBlock.CheckedContent>
+						<hc:ToggleBlock.UnCheckedContent>
+							<hc:Empty />
+						</hc:ToggleBlock.UnCheckedContent>
+					</hc:ToggleBlock>
 				</Border>
 			</Popup>
 			<TextBlock Grid.Column="0" Grid.ColumnSpan="2" FontSize="12" Text="{TemplateBinding ErrorStr}" Name="TextBlockError" VerticalAlignment="Bottom" Margin="9,0,0,4" Foreground="{DynamicResource DangerBrush}" Grid.Row="1" />
@@ -7151,10 +7147,6 @@
 				</MultiTrigger.Conditions>
 				<Setter Property="ScrollViewer.CanContentScroll" Value="false" />
 			</MultiTrigger>
-			<Trigger Property="ScrollViewer.CanContentScroll" SourceName="DropDownScrollViewer" Value="false">
-				<Setter Property="Canvas.Top" TargetName="opaqueRect" Value="{Binding VerticalOffset, ElementName=DropDownScrollViewer}" />
-				<Setter Property="Canvas.Left" TargetName="opaqueRect" Value="{Binding HorizontalOffset, ElementName=DropDownScrollViewer}" />
-			</Trigger>
 			<MultiTrigger>
 				<MultiTrigger.Conditions>
 					<Condition Property="IsMouseOver" Value="true" SourceName="toggleButton" />
@@ -7225,21 +7217,23 @@
 			</StackPanel>
 			<Popup Grid.Column="1" x:Name="PART_Popup" PlacementTarget="{Binding ElementName=toggleButton}" AllowsTransparency="true" Grid.ColumnSpan="2" StaysOpen="False" IsOpen="{Binding IsDropDownOpen, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}" Margin="1" PopupAnimation="{StaticResource {x:Static SystemParameters.ComboBoxPopupAnimationKey}}" Placement="Bottom">
 				<Border CornerRadius="{Binding Path=(hc:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
-					<Grid Margin="0,4" ClipToBounds="False">
-						<Grid.RowDefinitions>
-							<RowDefinition Height="Auto" />
-							<RowDefinition />
-						</Grid.RowDefinitions>
-						<hc:CheckComboBoxItem x:Name="PART_SelectAll" Style="{TemplateBinding ItemContainerStyle}" IsEnabled="{TemplateBinding ShowSelectAllButton}" Visibility="{Binding ShowSelectAllButton,RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}" HorizontalContentAlignment="Stretch" Content="{ex:Lang Key={x:Static langs:LangKeys.All}}" />
-						<ScrollViewer x:Name="DropDownScrollViewer" Grid.Row="1">
-							<hc:SimplePanel RenderOptions.ClearTypeHint="Enabled">
-								<Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
-									<Rectangle x:Name="opaqueRect" Fill="{Binding Background, ElementName=dropDownBorder}" Height="{Binding ActualHeight, ElementName=dropDownBorder}" Width="{Binding ActualWidth, ElementName=dropDownBorder}" />
-								</Canvas>
-								<ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
-							</hc:SimplePanel>
-						</ScrollViewer>
-					</Grid>
+					<hc:ToggleBlock IsChecked="{Binding HasItems,RelativeSource={RelativeSource TemplatedParent},Mode=OneWay}" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
+						<hc:ToggleBlock.CheckedContent>
+							<Grid Margin="0,4" ClipToBounds="False">
+								<Grid.RowDefinitions>
+									<RowDefinition Height="Auto" />
+									<RowDefinition />
+								</Grid.RowDefinitions>
+								<hc:CheckComboBoxItem x:Name="PART_SelectAll" Style="{TemplateBinding ItemContainerStyle}" IsEnabled="{TemplateBinding ShowSelectAllButton}" Visibility="{Binding ShowSelectAllButton,RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}" HorizontalContentAlignment="Stretch" Content="{ex:Lang Key={x:Static langs:LangKeys.All}}" />
+								<ScrollViewer x:Name="DropDownScrollViewer" Grid.Row="1">
+									<ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
+								</ScrollViewer>
+							</Grid>
+						</hc:ToggleBlock.CheckedContent>
+						<hc:ToggleBlock.UnCheckedContent>
+							<hc:Empty />
+						</hc:ToggleBlock.UnCheckedContent>
+					</hc:ToggleBlock>
 				</Border>
 			</Popup>
 			<TextBlock Grid.Column="1" Grid.ColumnSpan="2" FontSize="12" Text="{TemplateBinding ErrorStr}" Name="TextBlockError" VerticalAlignment="Bottom" Margin="9,0,0,4" Foreground="{DynamicResource DangerBrush}" />
@@ -7264,10 +7258,6 @@
 				</MultiTrigger.Conditions>
 				<Setter Property="ScrollViewer.CanContentScroll" Value="false" />
 			</MultiTrigger>
-			<Trigger Property="ScrollViewer.CanContentScroll" SourceName="DropDownScrollViewer" Value="false">
-				<Setter Property="Canvas.Top" TargetName="opaqueRect" Value="{Binding VerticalOffset, ElementName=DropDownScrollViewer}" />
-				<Setter Property="Canvas.Left" TargetName="opaqueRect" Value="{Binding HorizontalOffset, ElementName=DropDownScrollViewer}" />
-			</Trigger>
 			<MultiTrigger>
 				<MultiTrigger.Conditions>
 					<Condition Property="IsMouseOver" Value="true" SourceName="toggleButton" />