From 9f2f6883bee6199b620715aeddb1e7262ec0ff88 Mon Sep 17 00:00:00 2001
From: NaBian <836904362@qq.com>
Date: Thu, 10 Dec 2020 00:01:47 +0800
Subject: [PATCH] fixed #550

---
 .../Themes/Styles/Base/ComboBoxBaseStyle.xaml |  80 +++++++++++++++---
 .../Controls/Attach/DropDownElement.cs        |  10 +++
 .../Themes/Styles/Base/ComboBoxBaseStyle.xaml |  80 +++++++++++++++---
 .../Themes/XamlCombine.exe                    | Bin 13312 -> 13824 bytes
 4 files changed, 142 insertions(+), 28 deletions(-)

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 9154c735..524b1108 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
@@ -81,7 +81,7 @@
                 <ColumnDefinition Width="30"/>
             </Grid.ColumnDefinitions>
             <Popup x:Name="PART_Popup" PlacementTarget="{Binding ElementName=toggleButton}" AllowsTransparency="true" Grid.ColumnSpan="2" 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}">
+                <Border CornerRadius="{Binding Path=(hc:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MinWidth="{Binding ActualWidth, ElementName=toggleButton}" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
                     <ScrollViewer Margin="0,4" x:Name="DropDownScrollViewer">
                         <hc:SimplePanel RenderOptions.ClearTypeHint="Enabled">
                             <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
@@ -105,6 +105,10 @@
                 <Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
                 <Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
             </Trigger>
+            <Trigger Property="hc:DropDownElement.AutoWidth" Value="True">
+                <Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{x:Static system:Double.MaxValue}" />
+                <Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualHeight, 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}"/>
@@ -144,7 +148,7 @@
                 <ContentPresenter TextElement.Foreground="{DynamicResource DangerBrush}" Margin="4,0,0,0" Content="{Binding Path=(hc:InfoElement.Symbol),RelativeSource={RelativeSource TemplatedParent}}" Visibility="{Binding Path=(hc:InfoElement.Necessary),RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}"/>
             </StackPanel>
             <Popup Grid.Row="1" Grid.Column="0" x:Name="PART_Popup" PlacementTarget="{Binding ElementName=toggleButton}" AllowsTransparency="true" Grid.ColumnSpan="2" 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}">
+                <Border CornerRadius="{Binding Path=(hc:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MinWidth="{Binding ActualWidth, ElementName=toggleButton}" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
                     <ScrollViewer Margin="0,4" x:Name="DropDownScrollViewer">
                         <hc:SimplePanel RenderOptions.ClearTypeHint="Enabled">
                             <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
@@ -168,6 +172,10 @@
                 <Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
                 <Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
             </Trigger>
+            <Trigger Property="hc:DropDownElement.AutoWidth" Value="True">
+                <Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{x:Static system:Double.MaxValue}" />
+                <Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualHeight, 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}"/>
@@ -205,7 +213,7 @@
                 <ContentPresenter TextElement.Foreground="{DynamicResource DangerBrush}" Margin="4,0,0,0" Content="{Binding Path=(hc:InfoElement.Symbol),RelativeSource={RelativeSource TemplatedParent}}" Visibility="{Binding Path=(hc:InfoElement.Necessary),RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}"/>
             </StackPanel>
             <Popup Grid.Column="1" x:Name="PART_Popup" PlacementTarget="{Binding ElementName=toggleButton}" AllowsTransparency="true" Grid.ColumnSpan="2" 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}">
+                <Border CornerRadius="{Binding Path=(hc:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MinWidth="{Binding ActualWidth, ElementName=toggleButton}" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
                     <ScrollViewer Margin="0,4" x:Name="DropDownScrollViewer">
                         <hc:SimplePanel RenderOptions.ClearTypeHint="Enabled">
                             <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
@@ -229,6 +237,10 @@
                 <Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
                 <Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
             </Trigger>
+            <Trigger Property="hc:DropDownElement.AutoWidth" Value="True">
+                <Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{x:Static system:Double.MaxValue}" />
+                <Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualHeight, 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}"/>
@@ -280,7 +292,7 @@
                 <ColumnDefinition Width="30"/>
             </Grid.ColumnDefinitions>
             <Popup x:Name="PART_Popup" PlacementTarget="{Binding ElementName=toggleButton}" AllowsTransparency="true" Grid.ColumnSpan="2" IsOpen="{Binding IsDropDownOpen, RelativeSource={RelativeSource TemplatedParent}}" 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}">
+                <Border CornerRadius="{Binding Path=(hc:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MinWidth="{Binding ActualWidth, ElementName=toggleButton}" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
                     <ScrollViewer Margin="0,4" x:Name="DropDownScrollViewer">
                         <hc:SimplePanel RenderOptions.ClearTypeHint="Enabled">
                             <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
@@ -304,6 +316,10 @@
                 <Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
                 <Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
             </Trigger>
+            <Trigger Property="hc:DropDownElement.AutoWidth" Value="True">
+                <Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{x:Static system:Double.MaxValue}" />
+                <Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualHeight, 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}"/>
@@ -343,7 +359,7 @@
                 <ContentPresenter TextElement.Foreground="{DynamicResource DangerBrush}" Margin="4,0,0,0" Content="{Binding Path=(hc:InfoElement.Symbol),RelativeSource={RelativeSource TemplatedParent}}" Visibility="{Binding Path=(hc:InfoElement.Necessary),RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}"/>
             </StackPanel>
             <Popup Grid.Column="0" Grid.Row="1" x:Name="PART_Popup" PlacementTarget="{Binding ElementName=toggleButton}" AllowsTransparency="true" Grid.ColumnSpan="2" IsOpen="{Binding IsDropDownOpen, RelativeSource={RelativeSource TemplatedParent}}" 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}">
+                <Border CornerRadius="{Binding Path=(hc:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MinWidth="{Binding ActualWidth, ElementName=toggleButton}" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
                     <ScrollViewer Margin="0,4" x:Name="DropDownScrollViewer">
                         <hc:SimplePanel RenderOptions.ClearTypeHint="Enabled">
                             <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
@@ -367,6 +383,10 @@
                 <Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
                 <Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
             </Trigger>
+            <Trigger Property="hc:DropDownElement.AutoWidth" Value="True">
+                <Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{x:Static system:Double.MaxValue}" />
+                <Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualHeight, 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}"/>
@@ -404,7 +424,7 @@
                 <ContentPresenter TextElement.Foreground="{DynamicResource DangerBrush}" Margin="4,0,0,0" Content="{Binding Path=(hc:InfoElement.Symbol),RelativeSource={RelativeSource TemplatedParent}}" Visibility="{Binding Path=(hc:InfoElement.Necessary),RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}"/>
             </StackPanel>
             <Popup Grid.Column="1" x:Name="PART_Popup" PlacementTarget="{Binding ElementName=toggleButton}" AllowsTransparency="true" Grid.ColumnSpan="2" IsOpen="{Binding IsDropDownOpen, RelativeSource={RelativeSource TemplatedParent}}" 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}">
+                <Border CornerRadius="{Binding Path=(hc:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MinWidth="{Binding ActualWidth, ElementName=toggleButton}" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
                     <ScrollViewer Margin="0,4" x:Name="DropDownScrollViewer">
                         <hc:SimplePanel RenderOptions.ClearTypeHint="Enabled">
                             <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
@@ -428,6 +448,10 @@
                 <Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
                 <Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
             </Trigger>
+            <Trigger Property="hc:DropDownElement.AutoWidth" Value="True">
+                <Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{x:Static system:Double.MaxValue}" />
+                <Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualHeight, 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}"/>
@@ -574,7 +598,7 @@
                 <ContentPresenter TextElement.Foreground="{DynamicResource DangerBrush}" Margin="4,0,0,0" Content="{Binding Path=(hc:InfoElement.Symbol),RelativeSource={RelativeSource TemplatedParent}}" Visibility="{Binding Path=(hc:InfoElement.Necessary),RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}"/>
             </StackPanel>
             <Popup Grid.Row="1" Grid.Column="0" x:Name="PART_Popup" PlacementTarget="{Binding ElementName=toggleButton}" AllowsTransparency="true" Grid.ColumnSpan="2" 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}">
+                <Border CornerRadius="{Binding Path=(hc:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MinWidth="{Binding ActualWidth, ElementName=toggleButton}" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
                     <ScrollViewer Margin="0,4" x:Name="DropDownScrollViewer">
                         <hc:SimplePanel RenderOptions.ClearTypeHint="Enabled">
                             <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
@@ -600,6 +624,10 @@
                 <Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
                 <Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
             </Trigger>
+            <Trigger Property="hc:DropDownElement.AutoWidth" Value="True">
+                <Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{x:Static system:Double.MaxValue}" />
+                <Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualHeight, 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}"/>
@@ -675,7 +703,7 @@
                 <ContentPresenter TextElement.Foreground="{DynamicResource DangerBrush}" Margin="4,0,0,0" Content="{Binding Path=(hc:InfoElement.Symbol),RelativeSource={RelativeSource TemplatedParent}}" Visibility="{Binding Path=(hc:InfoElement.Necessary),RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}"/>
             </StackPanel>
             <Popup Grid.Column="1" x:Name="PART_Popup" PlacementTarget="{Binding ElementName=toggleButton}" AllowsTransparency="true" Grid.ColumnSpan="2" 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}">
+                <Border CornerRadius="{Binding Path=(hc:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MinWidth="{Binding ActualWidth, ElementName=toggleButton}" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
                     <ScrollViewer Margin="0,4" x:Name="DropDownScrollViewer">
                         <hc:SimplePanel RenderOptions.ClearTypeHint="Enabled">
                             <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
@@ -701,6 +729,10 @@
                 <Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
                 <Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
             </Trigger>
+            <Trigger Property="hc:DropDownElement.AutoWidth" Value="True">
+                <Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{x:Static system:Double.MaxValue}" />
+                <Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualHeight, 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}"/>
@@ -779,7 +811,7 @@
                 <ContentPresenter TextElement.Foreground="{DynamicResource DangerBrush}" Margin="4,0,0,0" Content="{Binding Path=(hc:InfoElement.Symbol),RelativeSource={RelativeSource TemplatedParent}}" Visibility="{Binding Path=(hc:InfoElement.Necessary),RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}"/>
             </StackPanel>
             <Popup Grid.Column="0" Grid.Row="1" x:Name="PART_Popup" PlacementTarget="{Binding ElementName=toggleButton}" AllowsTransparency="true" Grid.ColumnSpan="2" IsOpen="{Binding IsDropDownOpen, RelativeSource={RelativeSource TemplatedParent}}" 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}">
+                <Border CornerRadius="{Binding Path=(hc:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MinWidth="{Binding ActualWidth, ElementName=toggleButton}" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
                     <ScrollViewer Margin="0,4" x:Name="DropDownScrollViewer">
                         <hc:SimplePanel RenderOptions.ClearTypeHint="Enabled">
                             <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
@@ -805,6 +837,10 @@
                 <Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
                 <Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
             </Trigger>
+            <Trigger Property="hc:DropDownElement.AutoWidth" Value="True">
+                <Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{x:Static system:Double.MaxValue}" />
+                <Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualHeight, 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}"/>
@@ -900,7 +936,7 @@
                 <ContentPresenter TextElement.Foreground="{DynamicResource DangerBrush}" Margin="4,0,0,0" Content="{Binding Path=(hc:InfoElement.Symbol),RelativeSource={RelativeSource TemplatedParent}}" Visibility="{Binding Path=(hc:InfoElement.Necessary),RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}"/>
             </StackPanel>
             <Popup Grid.Column="0" Grid.Row="1" x:Name="PART_Popup" PlacementTarget="{Binding ElementName=toggleButton}" AllowsTransparency="true" Grid.ColumnSpan="2" IsOpen="{Binding IsDropDownOpen, RelativeSource={RelativeSource TemplatedParent}}" 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}">
+                <Border CornerRadius="{Binding Path=(hc:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MinWidth="{Binding ActualWidth, ElementName=toggleButton}" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
                     <ScrollViewer Margin="0,4" x:Name="DropDownScrollViewer">
                         <hc:SimplePanel RenderOptions.ClearTypeHint="Enabled">
                             <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
@@ -912,7 +948,7 @@
                 </Border>
             </Popup>
             <Popup Grid.Column="0" Grid.Row="1" x:Name="PART_Popup_AutoComplete" PlacementTarget="{Binding ElementName=toggleButton}" StaysOpen="False" 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_AutoComplete" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
+                <Border CornerRadius="{Binding Path=(hc:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder_AutoComplete" MinWidth="{Binding ActualWidth, ElementName=toggleButton}" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
                     <ScrollViewer Margin="0,4" x:Name="DropDownScrollViewer_AutoComplete">
                         <hc:SimplePanel RenderOptions.ClearTypeHint="Enabled">
                             <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
@@ -941,6 +977,12 @@
                 <Setter Property="MaxWidth" TargetName="dropDownBorder_AutoComplete" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
                 <Setter Property="MinWidth" TargetName="dropDownBorder_AutoComplete" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
             </Trigger>
+            <Trigger Property="hc:DropDownElement.AutoWidth" Value="True">
+                <Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{x:Static system:Double.MaxValue}" />
+                <Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualHeight, ElementName=toggleButton}" />
+                <Setter Property="MaxWidth" TargetName="dropDownBorder_AutoComplete" Value="{x:Static system:Double.MaxValue}" />
+                <Setter Property="MinWidth" TargetName="dropDownBorder_AutoComplete" Value="{Binding ActualHeight, 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}"/>
@@ -1038,7 +1080,7 @@
                 <ContentPresenter TextElement.Foreground="{DynamicResource DangerBrush}" Margin="4,0,0,0" Content="{Binding Path=(hc:InfoElement.Symbol),RelativeSource={RelativeSource TemplatedParent}}" Visibility="{Binding Path=(hc:InfoElement.Necessary),RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}"/>
             </StackPanel>
             <Popup Grid.Column="1" x:Name="PART_Popup" PlacementTarget="{Binding ElementName=toggleButton}" AllowsTransparency="true" Grid.ColumnSpan="2" IsOpen="{Binding IsDropDownOpen, RelativeSource={RelativeSource TemplatedParent}}" 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}">
+                <Border CornerRadius="{Binding Path=(hc:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MinWidth="{Binding ActualWidth, ElementName=toggleButton}" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
                     <ScrollViewer Margin="0,4" x:Name="DropDownScrollViewer">
                         <hc:SimplePanel RenderOptions.ClearTypeHint="Enabled">
                             <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
@@ -1064,6 +1106,10 @@
                 <Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
                 <Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
             </Trigger>
+            <Trigger Property="hc:DropDownElement.AutoWidth" Value="True">
+                <Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{x:Static system:Double.MaxValue}" />
+                <Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualHeight, 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}"/>
@@ -1156,7 +1202,7 @@
                 <ContentPresenter TextElement.Foreground="{DynamicResource DangerBrush}" Margin="4,0,0,0" Content="{Binding Path=(hc:InfoElement.Symbol),RelativeSource={RelativeSource TemplatedParent}}" Visibility="{Binding Path=(hc:InfoElement.Necessary),RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}"/>
             </StackPanel>
             <Popup Grid.Column="1" x:Name="PART_Popup" PlacementTarget="{Binding ElementName=toggleButton}" AllowsTransparency="true" Grid.ColumnSpan="2" IsOpen="{Binding IsDropDownOpen, RelativeSource={RelativeSource TemplatedParent}}" 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}">
+                <Border CornerRadius="{Binding Path=(hc:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MinWidth="{Binding ActualWidth, ElementName=toggleButton}" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
                     <ScrollViewer Margin="0,4" x:Name="DropDownScrollViewer">
                         <hc:SimplePanel RenderOptions.ClearTypeHint="Enabled">
                             <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
@@ -1168,7 +1214,7 @@
                 </Border>
             </Popup>
             <Popup Grid.Column="1" x:Name="PART_Popup_AutoComplete" PlacementTarget="{Binding ElementName=toggleButton}" 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_AutoComplete" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
+                <Border CornerRadius="{Binding Path=(hc:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder_AutoComplete" MinWidth="{Binding ActualWidth, ElementName=toggleButton}" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
                     <ScrollViewer Margin="0,4" x:Name="DropDownScrollViewer_AutoComplete">
                         <hc:SimplePanel RenderOptions.ClearTypeHint="Enabled">
                             <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
@@ -1197,6 +1243,12 @@
                 <Setter Property="MaxWidth" TargetName="dropDownBorder_AutoComplete" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
                 <Setter Property="MinWidth" TargetName="dropDownBorder_AutoComplete" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
             </Trigger>
+            <Trigger Property="hc:DropDownElement.AutoWidth" Value="True">
+                <Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{x:Static system:Double.MaxValue}" />
+                <Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualHeight, ElementName=toggleButton}" />
+                <Setter Property="MaxWidth" TargetName="dropDownBorder_AutoComplete" Value="{x:Static system:Double.MaxValue}" />
+                <Setter Property="MinWidth" TargetName="dropDownBorder_AutoComplete" Value="{Binding ActualHeight, 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}"/>
diff --git a/src/Shared/HandyControl_Shared/Controls/Attach/DropDownElement.cs b/src/Shared/HandyControl_Shared/Controls/Attach/DropDownElement.cs
index 8c70594a..3ac8d63b 100644
--- a/src/Shared/HandyControl_Shared/Controls/Attach/DropDownElement.cs
+++ b/src/Shared/HandyControl_Shared/Controls/Attach/DropDownElement.cs
@@ -14,5 +14,15 @@ namespace HandyControl.Controls
 
         public static bool GetConsistentWidth(DependencyObject element)
             => (bool) element.GetValue(ConsistentWidthProperty);
+
+        public static readonly DependencyProperty AutoWidthProperty = DependencyProperty.RegisterAttached(
+            "AutoWidth", typeof(bool), typeof(DropDownElement),
+            new FrameworkPropertyMetadata(ValueBoxes.FalseBox, FrameworkPropertyMetadataOptions.Inherits));
+
+        public static void SetAutoWidth(DependencyObject element, bool value)
+            => element.SetValue(AutoWidthProperty, value);
+
+        public static bool GetAutoWidth(DependencyObject element)
+            => (bool) element.GetValue(AutoWidthProperty);
     }
 }
diff --git a/src/Shared/HandyControl_Shared/Themes/Styles/Base/ComboBoxBaseStyle.xaml b/src/Shared/HandyControl_Shared/Themes/Styles/Base/ComboBoxBaseStyle.xaml
index 3ee766ca..97fddb20 100644
--- a/src/Shared/HandyControl_Shared/Themes/Styles/Base/ComboBoxBaseStyle.xaml
+++ b/src/Shared/HandyControl_Shared/Themes/Styles/Base/ComboBoxBaseStyle.xaml
@@ -81,7 +81,7 @@
                 <ColumnDefinition Width="30"/>
             </Grid.ColumnDefinitions>
             <Popup x:Name="PART_Popup" PlacementTarget="{Binding ElementName=toggleButton}" AllowsTransparency="true" Grid.ColumnSpan="2" 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}">
+                <Border CornerRadius="{Binding Path=(hc:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MinWidth="{Binding ActualWidth, ElementName=toggleButton}" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
                     <ScrollViewer Margin="0,4" x:Name="DropDownScrollViewer">
                         <hc:SimplePanel RenderOptions.ClearTypeHint="Enabled">
                             <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
@@ -105,6 +105,10 @@
                 <Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
                 <Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
             </Trigger>
+            <Trigger Property="hc:DropDownElement.AutoWidth" Value="True">
+                <Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{x:Static system:Double.MaxValue}" />
+                <Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualHeight, ElementName=toggleButton}" />
+            </Trigger>
             <MultiTrigger>
                 <MultiTrigger.Conditions>
                     <Condition Property="IsGrouping" Value="true"/>
@@ -151,7 +155,7 @@
                 <ContentPresenter TextElement.Foreground="{DynamicResource DangerBrush}" Margin="4,0,0,0" Content="{Binding Path=(hc:InfoElement.Symbol),RelativeSource={RelativeSource TemplatedParent}}" Visibility="{Binding Path=(hc:InfoElement.Necessary),RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}"/>
             </StackPanel>
             <Popup Grid.Row="1" Grid.Column="0" x:Name="PART_Popup" PlacementTarget="{Binding ElementName=toggleButton}" AllowsTransparency="true" Grid.ColumnSpan="2" 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}">
+                <Border CornerRadius="{Binding Path=(hc:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MinWidth="{Binding ActualWidth, ElementName=toggleButton}" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
                     <ScrollViewer Margin="0,4" x:Name="DropDownScrollViewer">
                         <hc:SimplePanel RenderOptions.ClearTypeHint="Enabled">
                             <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
@@ -175,6 +179,10 @@
                 <Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
                 <Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
             </Trigger>
+            <Trigger Property="hc:DropDownElement.AutoWidth" Value="True">
+                <Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{x:Static system:Double.MaxValue}" />
+                <Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualHeight, ElementName=toggleButton}" />
+            </Trigger>
             <MultiTrigger>
                 <MultiTrigger.Conditions>
                     <Condition Property="IsGrouping" Value="true"/>
@@ -219,7 +227,7 @@
                 <ContentPresenter TextElement.Foreground="{DynamicResource DangerBrush}" Margin="4,0,0,0" Content="{Binding Path=(hc:InfoElement.Symbol),RelativeSource={RelativeSource TemplatedParent}}" Visibility="{Binding Path=(hc:InfoElement.Necessary),RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}"/>
             </StackPanel>
             <Popup Grid.Column="1" x:Name="PART_Popup" PlacementTarget="{Binding ElementName=toggleButton}" AllowsTransparency="true" Grid.ColumnSpan="2" 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}">
+                <Border CornerRadius="{Binding Path=(hc:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MinWidth="{Binding ActualWidth, ElementName=toggleButton}" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
                     <ScrollViewer Margin="0,4" x:Name="DropDownScrollViewer">
                         <hc:SimplePanel RenderOptions.ClearTypeHint="Enabled">
                             <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
@@ -243,6 +251,10 @@
                 <Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
                 <Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
             </Trigger>
+            <Trigger Property="hc:DropDownElement.AutoWidth" Value="True">
+                <Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{x:Static system:Double.MaxValue}" />
+                <Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualHeight, ElementName=toggleButton}" />
+            </Trigger>
             <MultiTrigger>
                 <MultiTrigger.Conditions>
                     <Condition Property="IsGrouping" Value="true"/>
@@ -301,7 +313,7 @@
                 <ColumnDefinition Width="30"/>
             </Grid.ColumnDefinitions>
             <Popup x:Name="PART_Popup" PlacementTarget="{Binding ElementName=toggleButton}" AllowsTransparency="true" Grid.ColumnSpan="2" IsOpen="{Binding IsDropDownOpen, RelativeSource={RelativeSource TemplatedParent}}" 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}">
+                <Border CornerRadius="{Binding Path=(hc:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MinWidth="{Binding ActualWidth, ElementName=toggleButton}" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
                     <ScrollViewer Margin="0,4" x:Name="DropDownScrollViewer">
                         <hc:SimplePanel RenderOptions.ClearTypeHint="Enabled">
                             <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
@@ -325,6 +337,10 @@
                 <Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
                 <Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
             </Trigger>
+            <Trigger Property="hc:DropDownElement.AutoWidth" Value="True">
+                <Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{x:Static system:Double.MaxValue}" />
+                <Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualHeight, ElementName=toggleButton}" />
+            </Trigger>
             <MultiTrigger>
                 <MultiTrigger.Conditions>
                     <Condition Property="IsGrouping" Value="true"/>
@@ -371,7 +387,7 @@
                 <ContentPresenter TextElement.Foreground="{DynamicResource DangerBrush}" Margin="4,0,0,0" Content="{Binding Path=(hc:InfoElement.Symbol),RelativeSource={RelativeSource TemplatedParent}}" Visibility="{Binding Path=(hc:InfoElement.Necessary),RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}"/>
             </StackPanel>
             <Popup Grid.Column="0" Grid.Row="1" x:Name="PART_Popup" PlacementTarget="{Binding ElementName=toggleButton}" AllowsTransparency="true" Grid.ColumnSpan="2" IsOpen="{Binding IsDropDownOpen, RelativeSource={RelativeSource TemplatedParent}}" 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}">
+                <Border CornerRadius="{Binding Path=(hc:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MinWidth="{Binding ActualWidth, ElementName=toggleButton}" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
                     <ScrollViewer Margin="0,4" x:Name="DropDownScrollViewer">
                         <hc:SimplePanel RenderOptions.ClearTypeHint="Enabled">
                             <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
@@ -395,6 +411,10 @@
                 <Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
                 <Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
             </Trigger>
+            <Trigger Property="hc:DropDownElement.AutoWidth" Value="True">
+                <Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{x:Static system:Double.MaxValue}" />
+                <Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualHeight, ElementName=toggleButton}" />
+            </Trigger>
             <MultiTrigger>
                 <MultiTrigger.Conditions>
                     <Condition Property="IsGrouping" Value="true"/>
@@ -439,7 +459,7 @@
                 <ContentPresenter TextElement.Foreground="{DynamicResource DangerBrush}" Margin="4,0,0,0" Content="{Binding Path=(hc:InfoElement.Symbol),RelativeSource={RelativeSource TemplatedParent}}" Visibility="{Binding Path=(hc:InfoElement.Necessary),RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}"/>
             </StackPanel>
             <Popup Grid.Column="1" x:Name="PART_Popup" PlacementTarget="{Binding ElementName=toggleButton}" AllowsTransparency="true" Grid.ColumnSpan="2" IsOpen="{Binding IsDropDownOpen, RelativeSource={RelativeSource TemplatedParent}}" 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}">
+                <Border CornerRadius="{Binding Path=(hc:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MinWidth="{Binding ActualWidth, ElementName=toggleButton}" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
                     <ScrollViewer Margin="0,4" x:Name="DropDownScrollViewer">
                         <hc:SimplePanel RenderOptions.ClearTypeHint="Enabled">
                             <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
@@ -463,6 +483,10 @@
                 <Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
                 <Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
             </Trigger>
+            <Trigger Property="hc:DropDownElement.AutoWidth" Value="True">
+                <Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{x:Static system:Double.MaxValue}" />
+                <Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualHeight, ElementName=toggleButton}" />
+            </Trigger>
             <MultiTrigger>
                 <MultiTrigger.Conditions>
                     <Condition Property="IsGrouping" Value="true"/>
@@ -616,7 +640,7 @@
                 <ContentPresenter TextElement.Foreground="{DynamicResource DangerBrush}" Margin="4,0,0,0" Content="{Binding Path=(hc:InfoElement.Symbol),RelativeSource={RelativeSource TemplatedParent}}" Visibility="{Binding Path=(hc:InfoElement.Necessary),RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}"/>
             </StackPanel>
             <Popup Grid.Row="1" Grid.Column="0" x:Name="PART_Popup" PlacementTarget="{Binding ElementName=toggleButton}" AllowsTransparency="true" Grid.ColumnSpan="2" 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}">
+                <Border CornerRadius="{Binding Path=(hc:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MinWidth="{Binding ActualWidth, ElementName=toggleButton}" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
                     <ScrollViewer Margin="0,4" x:Name="DropDownScrollViewer">
                         <hc:SimplePanel RenderOptions.ClearTypeHint="Enabled">
                             <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
@@ -642,6 +666,10 @@
                 <Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
                 <Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
             </Trigger>
+            <Trigger Property="hc:DropDownElement.AutoWidth" Value="True">
+                <Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{x:Static system:Double.MaxValue}" />
+                <Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualHeight, ElementName=toggleButton}" />
+            </Trigger>
             <MultiTrigger>
                 <MultiTrigger.Conditions>
                     <Condition Property="IsGrouping" Value="true"/>
@@ -724,7 +752,7 @@
                 <ContentPresenter TextElement.Foreground="{DynamicResource DangerBrush}" Margin="4,0,0,0" Content="{Binding Path=(hc:InfoElement.Symbol),RelativeSource={RelativeSource TemplatedParent}}" Visibility="{Binding Path=(hc:InfoElement.Necessary),RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}"/>
             </StackPanel>
             <Popup Grid.Column="1" x:Name="PART_Popup" PlacementTarget="{Binding ElementName=toggleButton}" AllowsTransparency="true" Grid.ColumnSpan="2" 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}">
+                <Border CornerRadius="{Binding Path=(hc:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MinWidth="{Binding ActualWidth, ElementName=toggleButton}" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
                     <ScrollViewer Margin="0,4" x:Name="DropDownScrollViewer">
                         <hc:SimplePanel RenderOptions.ClearTypeHint="Enabled">
                             <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
@@ -750,6 +778,10 @@
                 <Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
                 <Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
             </Trigger>
+            <Trigger Property="hc:DropDownElement.AutoWidth" Value="True">
+                <Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{x:Static system:Double.MaxValue}" />
+                <Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualHeight, ElementName=toggleButton}" />
+            </Trigger>
             <MultiTrigger>
                 <MultiTrigger.Conditions>
                     <Condition Property="IsGrouping" Value="true"/>
@@ -835,7 +867,7 @@
                 <ContentPresenter TextElement.Foreground="{DynamicResource DangerBrush}" Margin="4,0,0,0" Content="{Binding Path=(hc:InfoElement.Symbol),RelativeSource={RelativeSource TemplatedParent}}" Visibility="{Binding Path=(hc:InfoElement.Necessary),RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}"/>
             </StackPanel>
             <Popup Grid.Column="0" Grid.Row="1" x:Name="PART_Popup" PlacementTarget="{Binding ElementName=toggleButton}" AllowsTransparency="true" Grid.ColumnSpan="2" IsOpen="{Binding IsDropDownOpen, RelativeSource={RelativeSource TemplatedParent}}" 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}">
+                <Border CornerRadius="{Binding Path=(hc:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MinWidth="{Binding ActualWidth, ElementName=toggleButton}" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
                     <ScrollViewer Margin="0,4" x:Name="DropDownScrollViewer">
                         <hc:SimplePanel RenderOptions.ClearTypeHint="Enabled">
                             <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
@@ -861,6 +893,10 @@
                 <Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
                 <Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
             </Trigger>
+            <Trigger Property="hc:DropDownElement.AutoWidth" Value="True">
+                <Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{x:Static system:Double.MaxValue}" />
+                <Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualHeight, ElementName=toggleButton}" />
+            </Trigger>
             <MultiTrigger>
                 <MultiTrigger.Conditions>
                     <Condition Property="IsGrouping" Value="true"/>
@@ -963,7 +999,7 @@
                 <ContentPresenter TextElement.Foreground="{DynamicResource DangerBrush}" Margin="4,0,0,0" Content="{Binding Path=(hc:InfoElement.Symbol),RelativeSource={RelativeSource TemplatedParent}}" Visibility="{Binding Path=(hc:InfoElement.Necessary),RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}"/>
             </StackPanel>
             <Popup Grid.Column="0" Grid.Row="1" x:Name="PART_Popup" PlacementTarget="{Binding ElementName=toggleButton}" AllowsTransparency="true" Grid.ColumnSpan="2" IsOpen="{Binding IsDropDownOpen, RelativeSource={RelativeSource TemplatedParent}}" 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}">
+                <Border CornerRadius="{Binding Path=(hc:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MinWidth="{Binding ActualWidth, ElementName=toggleButton}" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
                     <ScrollViewer Margin="0,4" x:Name="DropDownScrollViewer">
                         <hc:SimplePanel RenderOptions.ClearTypeHint="Enabled">
                             <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
@@ -975,7 +1011,7 @@
                 </Border>
             </Popup>
             <Popup Grid.Column="0" Grid.Row="1" x:Name="PART_Popup_AutoComplete" PlacementTarget="{Binding ElementName=toggleButton}" StaysOpen="False" 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_AutoComplete" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
+                <Border CornerRadius="{Binding Path=(hc:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder_AutoComplete" MinWidth="{Binding ActualWidth, ElementName=toggleButton}" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
                     <ScrollViewer Margin="0,4" x:Name="DropDownScrollViewer_AutoComplete">
                         <hc:SimplePanel RenderOptions.ClearTypeHint="Enabled">
                             <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
@@ -1004,6 +1040,12 @@
                 <Setter Property="MaxWidth" TargetName="dropDownBorder_AutoComplete" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
                 <Setter Property="MinWidth" TargetName="dropDownBorder_AutoComplete" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
             </Trigger>
+            <Trigger Property="hc:DropDownElement.AutoWidth" Value="True">
+                <Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{x:Static system:Double.MaxValue}" />
+                <Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualHeight, ElementName=toggleButton}" />
+                <Setter Property="MaxWidth" TargetName="dropDownBorder_AutoComplete" Value="{x:Static system:Double.MaxValue}" />
+                <Setter Property="MinWidth" TargetName="dropDownBorder_AutoComplete" Value="{Binding ActualHeight, ElementName=toggleButton}" />
+            </Trigger>
             <MultiTrigger>
                 <MultiTrigger.Conditions>
                     <Condition Property="IsGrouping" Value="true"/>
@@ -1108,7 +1150,7 @@
                 <ContentPresenter TextElement.Foreground="{DynamicResource DangerBrush}" Margin="4,0,0,0" Content="{Binding Path=(hc:InfoElement.Symbol),RelativeSource={RelativeSource TemplatedParent}}" Visibility="{Binding Path=(hc:InfoElement.Necessary),RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}"/>
             </StackPanel>
             <Popup Grid.Column="1" x:Name="PART_Popup" PlacementTarget="{Binding ElementName=toggleButton}" AllowsTransparency="true" Grid.ColumnSpan="2" IsOpen="{Binding IsDropDownOpen, RelativeSource={RelativeSource TemplatedParent}}" 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}">
+                <Border CornerRadius="{Binding Path=(hc:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MinWidth="{Binding ActualWidth, ElementName=toggleButton}" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
                     <ScrollViewer Margin="0,4" x:Name="DropDownScrollViewer">
                         <hc:SimplePanel RenderOptions.ClearTypeHint="Enabled">
                             <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
@@ -1134,6 +1176,10 @@
                 <Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
                 <Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
             </Trigger>
+            <Trigger Property="hc:DropDownElement.AutoWidth" Value="True">
+                <Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{x:Static system:Double.MaxValue}" />
+                <Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualHeight, ElementName=toggleButton}" />
+            </Trigger>
             <MultiTrigger>
                 <MultiTrigger.Conditions>
                     <Condition Property="IsGrouping" Value="true"/>
@@ -1233,7 +1279,7 @@
                 <ContentPresenter TextElement.Foreground="{DynamicResource DangerBrush}" Margin="4,0,0,0" Content="{Binding Path=(hc:InfoElement.Symbol),RelativeSource={RelativeSource TemplatedParent}}" Visibility="{Binding Path=(hc:InfoElement.Necessary),RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}"/>
             </StackPanel>
             <Popup Grid.Column="1" x:Name="PART_Popup" PlacementTarget="{Binding ElementName=toggleButton}" AllowsTransparency="true" Grid.ColumnSpan="2" IsOpen="{Binding IsDropDownOpen, RelativeSource={RelativeSource TemplatedParent}}" 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}">
+                <Border CornerRadius="{Binding Path=(hc:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MinWidth="{Binding ActualWidth, ElementName=toggleButton}" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
                     <ScrollViewer Margin="0,4" x:Name="DropDownScrollViewer">
                         <hc:SimplePanel RenderOptions.ClearTypeHint="Enabled">
                             <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
@@ -1245,7 +1291,7 @@
                 </Border>
             </Popup>
             <Popup Grid.Column="1" x:Name="PART_Popup_AutoComplete" PlacementTarget="{Binding ElementName=toggleButton}" 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_AutoComplete" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
+                <Border CornerRadius="{Binding Path=(hc:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder_AutoComplete" MinWidth="{Binding ActualWidth, ElementName=toggleButton}" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
                     <ScrollViewer Margin="0,4" x:Name="DropDownScrollViewer_AutoComplete">
                         <hc:SimplePanel RenderOptions.ClearTypeHint="Enabled">
                             <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
@@ -1274,6 +1320,12 @@
                 <Setter Property="MaxWidth" TargetName="dropDownBorder_AutoComplete" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
                 <Setter Property="MinWidth" TargetName="dropDownBorder_AutoComplete" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
             </Trigger>
+            <Trigger Property="hc:DropDownElement.AutoWidth" Value="True">
+                <Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{x:Static system:Double.MaxValue}" />
+                <Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualHeight, ElementName=toggleButton}" />
+                <Setter Property="MaxWidth" TargetName="dropDownBorder_AutoComplete" Value="{x:Static system:Double.MaxValue}" />
+                <Setter Property="MinWidth" TargetName="dropDownBorder_AutoComplete" Value="{Binding ActualHeight, ElementName=toggleButton}" />
+            </Trigger>
             <MultiTrigger>
                 <MultiTrigger.Conditions>
                     <Condition Property="IsGrouping" Value="true"/>
diff --git a/src/Shared/HandyControl_Shared/Themes/XamlCombine.exe b/src/Shared/HandyControl_Shared/Themes/XamlCombine.exe
index c88411e4e48ae85194751e840744a596d14536be..44f393d3a274a155aea1b77f7c8c9fb59796d235 100644
GIT binary patch
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