From 61ee9a533790b53897f72dc88e8700df0548cdeb Mon Sep 17 00:00:00 2001
From: NaBian <836904362@qq.com>
Date: Sun, 19 Apr 2020 13:29:19 +0800
Subject: [PATCH] close #362

---
 .../Themes/Styles/Base/ComboBoxBaseStyle.xaml | 108 +++++++++++++-----
 .../Styles/NativeComboBoxDemoCtl.xaml         |   4 +-
 .../Controls/Attach/DropDownElement.cs        |  18 +++
 .../HandyControl_Shared.projitems             |   1 +
 .../Themes/Styles/Base/ComboBoxBaseStyle.xaml | 108 +++++++++++++-----
 5 files changed, 181 insertions(+), 58 deletions(-)
 create mode 100644 src/Shared/HandyControl_Shared/Controls/Attach/DropDownElement.cs

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 221e66e8..dd91d422 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
@@ -79,8 +79,8 @@
                 <ColumnDefinition/>
                 <ColumnDefinition Width="30"/>
             </Grid.ColumnDefinitions>
-            <Popup x:Name="PART_Popup" 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=(controls:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" MinWidth="{Binding ActualWidth, ElementName=templateRoot}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
+            <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=(controls:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
                     <ScrollViewer Margin="0,4" x:Name="DropDownScrollViewer">
                         <controls:SimplePanel RenderOptions.ClearTypeHint="Enabled">
                             <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
@@ -100,6 +100,10 @@
             <Trigger Property="HasItems" Value="false">
                 <Setter Property="Height" TargetName="dropDownBorder" Value="95"/>
             </Trigger>
+            <Trigger Property="controls:DropDownElement.ConsistentWidth" Value="True">
+                <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}"/>
@@ -138,8 +142,8 @@
                 <TextBlock Margin="1,0,0,0" Text="{Binding Path=(controls:InfoElement.Title),RelativeSource={RelativeSource TemplatedParent}}"/>
                 <ContentPresenter TextElement.Foreground="{DynamicResource DangerBrush}" Margin="4,0,0,0" Content="{Binding Path=(controls:InfoElement.Symbol),RelativeSource={RelativeSource TemplatedParent}}" Visibility="{Binding Path=(controls:InfoElement.Necessary),RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}"/>
             </StackPanel>
-            <Popup Grid.Row="1" Grid.Column="0" x:Name="PART_Popup" 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=(controls:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" MinWidth="{Binding ActualWidth, ElementName=toggleButton}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
+            <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=(controls:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
                     <ScrollViewer Margin="0,4" x:Name="DropDownScrollViewer">
                         <controls:SimplePanel RenderOptions.ClearTypeHint="Enabled">
                             <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
@@ -159,6 +163,10 @@
             <Trigger Property="HasItems" Value="false">
                 <Setter Property="Height" TargetName="dropDownBorder" Value="95"/>
             </Trigger>
+            <Trigger Property="controls:DropDownElement.ConsistentWidth" Value="True">
+                <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}"/>
@@ -195,8 +203,8 @@
                 <TextBlock Text="{Binding Path=(controls:InfoElement.Title),RelativeSource={RelativeSource TemplatedParent}}"/>
                 <ContentPresenter TextElement.Foreground="{DynamicResource DangerBrush}" Margin="4,0,0,0" Content="{Binding Path=(controls:InfoElement.Symbol),RelativeSource={RelativeSource TemplatedParent}}" Visibility="{Binding Path=(controls:InfoElement.Necessary),RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}"/>
             </StackPanel>
-            <Popup Grid.Column="1" x:Name="PART_Popup" 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=(controls:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" MinWidth="{Binding ActualWidth, ElementName=templateRoot}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
+            <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=(controls:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
                     <ScrollViewer Margin="0,4" x:Name="DropDownScrollViewer">
                         <controls:SimplePanel RenderOptions.ClearTypeHint="Enabled">
                             <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
@@ -216,6 +224,10 @@
             <Trigger Property="HasItems" Value="false">
                 <Setter Property="Height" TargetName="dropDownBorder" Value="95"/>
             </Trigger>
+            <Trigger Property="controls:DropDownElement.ConsistentWidth" Value="True">
+                <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}"/>
@@ -266,8 +278,8 @@
                 <ColumnDefinition/>
                 <ColumnDefinition Width="30"/>
             </Grid.ColumnDefinitions>
-            <Popup x:Name="PART_Popup" AllowsTransparency="true" Grid.ColumnSpan="2" IsOpen="{Binding IsDropDownOpen, RelativeSource={RelativeSource TemplatedParent}}" PopupAnimation="{StaticResource {x:Static SystemParameters.ComboBoxPopupAnimationKey}}" Placement="Bottom">
-                <Border CornerRadius="{Binding Path=(controls:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" MinWidth="{Binding ActualWidth, ElementName=templateRoot}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
+            <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=(controls:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
                     <ScrollViewer Margin="0,4" x:Name="DropDownScrollViewer">
                         <controls:SimplePanel RenderOptions.ClearTypeHint="Enabled">
                             <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
@@ -287,6 +299,10 @@
             <Trigger Property="HasItems" Value="false">
                 <Setter Property="Height" TargetName="dropDownBorder" Value="95"/>
             </Trigger>
+            <Trigger Property="controls:DropDownElement.ConsistentWidth" Value="True">
+                <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}"/>
@@ -325,8 +341,8 @@
                 <TextBlock Margin="1,0,0,0" Text="{Binding Path=(controls:InfoElement.Title),RelativeSource={RelativeSource TemplatedParent}}"/>
                 <ContentPresenter TextElement.Foreground="{DynamicResource DangerBrush}" Margin="4,0,0,0" Content="{Binding Path=(controls:InfoElement.Symbol),RelativeSource={RelativeSource TemplatedParent}}" Visibility="{Binding Path=(controls:InfoElement.Necessary),RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}"/>
             </StackPanel>
-            <Popup Grid.Column="0" Grid.Row="1" x:Name="PART_Popup" AllowsTransparency="true" Grid.ColumnSpan="2" IsOpen="{Binding IsDropDownOpen, RelativeSource={RelativeSource TemplatedParent}}" PopupAnimation="{StaticResource {x:Static SystemParameters.ComboBoxPopupAnimationKey}}" Placement="Bottom">
-                <Border CornerRadius="{Binding Path=(controls:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" MinWidth="{Binding ActualWidth, ElementName=templateRoot}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
+            <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=(controls:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
                     <ScrollViewer Margin="0,4" x:Name="DropDownScrollViewer">
                         <controls:SimplePanel RenderOptions.ClearTypeHint="Enabled">
                             <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
@@ -346,6 +362,10 @@
             <Trigger Property="HasItems" Value="false">
                 <Setter Property="Height" TargetName="dropDownBorder" Value="95"/>
             </Trigger>
+            <Trigger Property="controls:DropDownElement.ConsistentWidth" Value="True">
+                <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}"/>
@@ -382,8 +402,8 @@
                 <TextBlock Text="{Binding Path=(controls:InfoElement.Title),RelativeSource={RelativeSource TemplatedParent}}"/>
                 <ContentPresenter TextElement.Foreground="{DynamicResource DangerBrush}" Margin="4,0,0,0" Content="{Binding Path=(controls:InfoElement.Symbol),RelativeSource={RelativeSource TemplatedParent}}" Visibility="{Binding Path=(controls:InfoElement.Necessary),RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}"/>
             </StackPanel>
-            <Popup Grid.Column="1" x:Name="PART_Popup" AllowsTransparency="true" Grid.ColumnSpan="2" IsOpen="{Binding IsDropDownOpen, RelativeSource={RelativeSource TemplatedParent}}" PopupAnimation="{StaticResource {x:Static SystemParameters.ComboBoxPopupAnimationKey}}" Placement="Bottom">
-                <Border CornerRadius="{Binding Path=(controls:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" MinWidth="{Binding ActualWidth, ElementName=templateRoot}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
+            <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=(controls:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
                     <ScrollViewer Margin="0,4" x:Name="DropDownScrollViewer">
                         <controls:SimplePanel RenderOptions.ClearTypeHint="Enabled">
                             <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
@@ -403,6 +423,10 @@
             <Trigger Property="HasItems" Value="false">
                 <Setter Property="Height" TargetName="dropDownBorder" Value="95"/>
             </Trigger>
+            <Trigger Property="controls:DropDownElement.ConsistentWidth" Value="True">
+                <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}"/>
@@ -548,8 +572,8 @@
                 <TextBlock Margin="1,0,0,0" Text="{Binding Path=(controls:InfoElement.Title),RelativeSource={RelativeSource TemplatedParent}}"/>
                 <ContentPresenter TextElement.Foreground="{DynamicResource DangerBrush}" Margin="4,0,0,0" Content="{Binding Path=(controls:InfoElement.Symbol),RelativeSource={RelativeSource TemplatedParent}}" Visibility="{Binding Path=(controls:InfoElement.Necessary),RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}"/>
             </StackPanel>
-            <Popup Grid.Row="1" Grid.Column="0" x:Name="PART_Popup" 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=(controls:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" MinWidth="{Binding ActualWidth, ElementName=toggleButton}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
+            <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=(controls:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
                     <ScrollViewer Margin="0,4" x:Name="DropDownScrollViewer">
                         <controls:SimplePanel RenderOptions.ClearTypeHint="Enabled">
                             <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
@@ -571,6 +595,10 @@
             <Trigger Property="HasItems" Value="false">
                 <Setter Property="Height" TargetName="dropDownBorder" Value="95"/>
             </Trigger>
+            <Trigger Property="controls:DropDownElement.ConsistentWidth" Value="True">
+                <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}"/>
@@ -645,8 +673,8 @@
                 <TextBlock Text="{Binding Path=(controls:InfoElement.Title),RelativeSource={RelativeSource TemplatedParent}}"/>
                 <ContentPresenter TextElement.Foreground="{DynamicResource DangerBrush}" Margin="4,0,0,0" Content="{Binding Path=(controls:InfoElement.Symbol),RelativeSource={RelativeSource TemplatedParent}}" Visibility="{Binding Path=(controls:InfoElement.Necessary),RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}"/>
             </StackPanel>
-            <Popup Grid.Column="1" x:Name="PART_Popup" 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=(controls:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" MinWidth="{Binding ActualWidth, ElementName=templateRoot}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
+            <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=(controls:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
                     <ScrollViewer Margin="0,4" x:Name="DropDownScrollViewer">
                         <controls:SimplePanel RenderOptions.ClearTypeHint="Enabled">
                             <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
@@ -668,6 +696,10 @@
             <Trigger Property="HasItems" Value="false">
                 <Setter Property="Height" TargetName="dropDownBorder" Value="95"/>
             </Trigger>
+            <Trigger Property="controls:DropDownElement.ConsistentWidth" Value="True">
+                <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}"/>
@@ -745,8 +777,8 @@
                 <TextBlock Margin="1,0,0,0" Text="{Binding Path=(controls:InfoElement.Title),RelativeSource={RelativeSource TemplatedParent}}"/>
                 <ContentPresenter TextElement.Foreground="{DynamicResource DangerBrush}" Margin="4,0,0,0" Content="{Binding Path=(controls:InfoElement.Symbol),RelativeSource={RelativeSource TemplatedParent}}" Visibility="{Binding Path=(controls:InfoElement.Necessary),RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}"/>
             </StackPanel>
-            <Popup Grid.Column="0" Grid.Row="1" x:Name="PART_Popup" AllowsTransparency="true" Grid.ColumnSpan="2" IsOpen="{Binding IsDropDownOpen, RelativeSource={RelativeSource TemplatedParent}}" PopupAnimation="{StaticResource {x:Static SystemParameters.ComboBoxPopupAnimationKey}}" Placement="Bottom">
-                <Border CornerRadius="{Binding Path=(controls:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" MinWidth="{Binding ActualWidth, ElementName=templateRoot}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
+            <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=(controls:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
                     <ScrollViewer Margin="0,4" x:Name="DropDownScrollViewer">
                         <controls:SimplePanel RenderOptions.ClearTypeHint="Enabled">
                             <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
@@ -768,6 +800,10 @@
             <Trigger Property="HasItems" Value="false">
                 <Setter Property="Height" TargetName="dropDownBorder" Value="95"/>
             </Trigger>
+            <Trigger Property="controls:DropDownElement.ConsistentWidth" Value="True">
+                <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}"/>
@@ -862,8 +898,8 @@
                 <TextBlock Margin="1,0,0,0" Text="{Binding Path=(controls:InfoElement.Title),RelativeSource={RelativeSource TemplatedParent}}"/>
                 <ContentPresenter TextElement.Foreground="{DynamicResource DangerBrush}" Margin="4,0,0,0" Content="{Binding Path=(controls:InfoElement.Symbol),RelativeSource={RelativeSource TemplatedParent}}" Visibility="{Binding Path=(controls:InfoElement.Necessary),RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}"/>
             </StackPanel>
-            <Popup Grid.Column="0" Grid.Row="1" x:Name="PART_Popup" AllowsTransparency="true" Grid.ColumnSpan="2" IsOpen="{Binding IsDropDownOpen, RelativeSource={RelativeSource TemplatedParent}}" PopupAnimation="{StaticResource {x:Static SystemParameters.ComboBoxPopupAnimationKey}}" Placement="Bottom">
-                <Border CornerRadius="{Binding Path=(controls:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" MinWidth="{Binding ActualWidth, ElementName=templateRoot}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
+            <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=(controls:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
                     <ScrollViewer Margin="0,4" x:Name="DropDownScrollViewer">
                         <controls:SimplePanel RenderOptions.ClearTypeHint="Enabled">
                             <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
@@ -874,8 +910,8 @@
                     </ScrollViewer>
                 </Border>
             </Popup>
-            <Popup Grid.Column="0" Grid.Row="1" x:Name="PART_Popup_AutoComplete" StaysOpen="False" AllowsTransparency="true" Grid.ColumnSpan="2" PopupAnimation="{StaticResource {x:Static SystemParameters.ComboBoxPopupAnimationKey}}" Placement="Bottom">
-                <Border CornerRadius="{Binding Path=(controls:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder_AutoComplete" MaxHeight="{TemplateBinding MaxDropDownHeight}" MinWidth="{Binding ActualWidth, ElementName=templateRoot}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
+            <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=(controls:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder_AutoComplete" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
                     <ScrollViewer Margin="0,4" x:Name="DropDownScrollViewer_AutoComplete">
                         <controls:SimplePanel RenderOptions.ClearTypeHint="Enabled">
                             <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
@@ -898,6 +934,12 @@
                 <Setter Property="Height" TargetName="dropDownBorder" Value="95"/>
                 <Setter Property="Height" TargetName="dropDownBorder_AutoComplete" Value="95"/>
             </Trigger>
+            <Trigger Property="controls:DropDownElement.ConsistentWidth" Value="True">
+                <Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
+                <Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
+                <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="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}"/>
@@ -994,8 +1036,8 @@
                 <TextBlock Text="{Binding Path=(controls:InfoElement.Title),RelativeSource={RelativeSource TemplatedParent}}"/>
                 <ContentPresenter TextElement.Foreground="{DynamicResource DangerBrush}" Margin="4,0,0,0" Content="{Binding Path=(controls:InfoElement.Symbol),RelativeSource={RelativeSource TemplatedParent}}" Visibility="{Binding Path=(controls:InfoElement.Necessary),RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}"/>
             </StackPanel>
-            <Popup Grid.Column="1" x:Name="PART_Popup" AllowsTransparency="true" Grid.ColumnSpan="2" IsOpen="{Binding IsDropDownOpen, RelativeSource={RelativeSource TemplatedParent}}" PopupAnimation="{StaticResource {x:Static SystemParameters.ComboBoxPopupAnimationKey}}" Placement="Bottom">
-                <Border CornerRadius="{Binding Path=(controls:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" MinWidth="{Binding ActualWidth, ElementName=templateRoot}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
+            <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=(controls:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
                     <ScrollViewer Margin="0,4" x:Name="DropDownScrollViewer">
                         <controls:SimplePanel RenderOptions.ClearTypeHint="Enabled">
                             <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
@@ -1017,6 +1059,10 @@
             <Trigger Property="HasItems" Value="false">
                 <Setter Property="Height" TargetName="dropDownBorder" Value="95"/>
             </Trigger>
+            <Trigger Property="controls:DropDownElement.ConsistentWidth" Value="True">
+                <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}"/>
@@ -1108,8 +1154,8 @@
                 <TextBlock Text="{Binding Path=(controls:InfoElement.Title),RelativeSource={RelativeSource TemplatedParent}}"/>
                 <ContentPresenter TextElement.Foreground="{DynamicResource DangerBrush}" Margin="4,0,0,0" Content="{Binding Path=(controls:InfoElement.Symbol),RelativeSource={RelativeSource TemplatedParent}}" Visibility="{Binding Path=(controls:InfoElement.Necessary),RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}"/>
             </StackPanel>
-            <Popup Grid.Column="1" x:Name="PART_Popup" AllowsTransparency="true" Grid.ColumnSpan="2" IsOpen="{Binding IsDropDownOpen, RelativeSource={RelativeSource TemplatedParent}}" PopupAnimation="{StaticResource {x:Static SystemParameters.ComboBoxPopupAnimationKey}}" Placement="Bottom">
-                <Border CornerRadius="{Binding Path=(controls:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" MinWidth="{Binding ActualWidth, ElementName=templateRoot}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
+            <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=(controls:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
                     <ScrollViewer Margin="0,4" x:Name="DropDownScrollViewer">
                         <controls:SimplePanel RenderOptions.ClearTypeHint="Enabled">
                             <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
@@ -1120,8 +1166,8 @@
                     </ScrollViewer>
                 </Border>
             </Popup>
-            <Popup Grid.Column="1" x:Name="PART_Popup_AutoComplete" AllowsTransparency="true" Grid.ColumnSpan="2" PopupAnimation="{StaticResource {x:Static SystemParameters.ComboBoxPopupAnimationKey}}" Placement="Bottom">
-                <Border CornerRadius="{Binding Path=(controls:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder_AutoComplete" MaxHeight="{TemplateBinding MaxDropDownHeight}" MinWidth="{Binding ActualWidth, ElementName=templateRoot}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
+            <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=(controls:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder_AutoComplete" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
                     <ScrollViewer Margin="0,4" x:Name="DropDownScrollViewer_AutoComplete">
                         <controls:SimplePanel RenderOptions.ClearTypeHint="Enabled">
                             <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
@@ -1144,6 +1190,12 @@
                 <Setter Property="Height" TargetName="dropDownBorder" Value="95"/>
                 <Setter Property="Height" TargetName="dropDownBorder_AutoComplete" Value="95"/>
             </Trigger>
+            <Trigger Property="controls:DropDownElement.ConsistentWidth" Value="True">
+                <Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
+                <Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
+                <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="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/HandyControlDemo_Shared/UserControl/Styles/NativeComboBoxDemoCtl.xaml b/src/Shared/HandyControlDemo_Shared/UserControl/Styles/NativeComboBoxDemoCtl.xaml
index 709828a3..c5dd74a5 100644
--- a/src/Shared/HandyControlDemo_Shared/UserControl/Styles/NativeComboBoxDemoCtl.xaml
+++ b/src/Shared/HandyControlDemo_Shared/UserControl/Styles/NativeComboBoxDemoCtl.xaml
@@ -9,11 +9,11 @@
     <hc:TransitioningContentControl>
         <ScrollViewer>
             <StackPanel Margin="32">
-                <ComboBox ItemsSource="{Binding DataList}" SelectedIndex="0"/>
+                <ComboBox hc:DropDownElement.ConsistentWidth="False" ItemsSource="{Binding DataList}" SelectedIndex="0"/>
                 <ComboBox ItemsSource="{Binding DataList}" Margin="0,16,0,0" SelectedIndex="0" IsEnabled="False"/>
                 <ComboBox ItemsSource="{Binding DataList}" SelectedIndex="0" Margin="0,16,0,0" IsEditable="True"/>
 
-                <ComboBox ItemsSource="{Binding DataList}" SelectedIndex="0" hc:InfoElement.Title="{ex:Lang Key={x:Static langs:LangKeys.TitleDemoStr1}}" Style="{StaticResource ComboBoxExtend}" Margin="0,32,0,0" Text="{ex:Lang Key={x:Static langs:LangKeys.ContentDemoStr}}"/>
+                <ComboBox hc:DropDownElement.ConsistentWidth="False" ItemsSource="{Binding DataList}" SelectedIndex="0" hc:InfoElement.Title="{ex:Lang Key={x:Static langs:LangKeys.TitleDemoStr1}}" Style="{StaticResource ComboBoxExtend}" Margin="0,32,0,0" Text="{ex:Lang Key={x:Static langs:LangKeys.ContentDemoStr}}"/>
                 <ComboBox ItemsSource="{Binding DataList}" hc:InfoElement.Placeholder="{ex:Lang Key={x:Static langs:LangKeys.PlsEnterContent}}" hc:InfoElement.Title="{ex:Lang Key={x:Static langs:LangKeys.TitleDemoStr2}}" Style="{StaticResource ComboBoxExtend}" hc:InfoElement.Necessary="True" hc:InfoElement.Symbol="*" Margin="0,16,0,0"/>
                 <ComboBox ItemsSource="{Binding DataList}" IsEditable="True" SelectedIndex="0" hc:InfoElement.Title="{ex:Lang Key={x:Static langs:LangKeys.TitleDemoStr1}}" Style="{StaticResource ComboBoxExtend}" Margin="0,16,0,0" Text="{ex:Lang Key={x:Static langs:LangKeys.ContentDemoStr}}"/>
                 <ComboBox ItemsSource="{Binding DataList}" IsEditable="True" hc:InfoElement.Placeholder="{ex:Lang Key={x:Static langs:LangKeys.PlsEnterContent}}" hc:InfoElement.Title="{ex:Lang Key={x:Static langs:LangKeys.TitleDemoStr2}}" Style="{StaticResource ComboBoxExtend}" hc:InfoElement.Necessary="True" Margin="0,16,0,0"/>
diff --git a/src/Shared/HandyControl_Shared/Controls/Attach/DropDownElement.cs b/src/Shared/HandyControl_Shared/Controls/Attach/DropDownElement.cs
new file mode 100644
index 00000000..cb88e93e
--- /dev/null
+++ b/src/Shared/HandyControl_Shared/Controls/Attach/DropDownElement.cs
@@ -0,0 +1,18 @@
+using System.Windows;
+using HandyControl.Data;
+
+namespace HandyControl.Controls
+{
+    public class DropDownElement
+    {
+        public static readonly DependencyProperty ConsistentWidthProperty = DependencyProperty.RegisterAttached(
+            "ConsistentWidth", typeof(bool), typeof(DropDownElement),
+            new FrameworkPropertyMetadata(ValueBoxes.TrueBox, FrameworkPropertyMetadataOptions.Inherits));
+
+        public static void SetConsistentWidth(DependencyObject element, bool value)
+            => element.SetValue(ConsistentWidthProperty, value);
+
+        public static bool GetConsistentWidth(DependencyObject element)
+            => (bool) element.GetValue(ConsistentWidthProperty);
+    }
+}
diff --git a/src/Shared/HandyControl_Shared/HandyControl_Shared.projitems b/src/Shared/HandyControl_Shared/HandyControl_Shared.projitems
index 9e017186..7fd0cd13 100644
--- a/src/Shared/HandyControl_Shared/HandyControl_Shared.projitems
+++ b/src/Shared/HandyControl_Shared/HandyControl_Shared.projitems
@@ -13,6 +13,7 @@
     <Compile Include="$(MSBuildThisFileDirectory)Controls\Attach\BackgroundSwitchElement.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Controls\Attach\BorderElement.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Controls\Attach\DataGridAttach.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)Controls\Attach\DropDownElement.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Controls\Attach\EdgeElement.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Controls\Attach\IconElement.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Controls\Attach\IconSwitchElement.cs" />
diff --git a/src/Shared/HandyControl_Shared/Themes/Styles/Base/ComboBoxBaseStyle.xaml b/src/Shared/HandyControl_Shared/Themes/Styles/Base/ComboBoxBaseStyle.xaml
index c12c3416..d54c1e3a 100644
--- a/src/Shared/HandyControl_Shared/Themes/Styles/Base/ComboBoxBaseStyle.xaml
+++ b/src/Shared/HandyControl_Shared/Themes/Styles/Base/ComboBoxBaseStyle.xaml
@@ -79,8 +79,8 @@
                 <ColumnDefinition/>
                 <ColumnDefinition Width="30"/>
             </Grid.ColumnDefinitions>
-            <Popup x:Name="PART_Popup" 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=(controls:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" MinWidth="{Binding ActualWidth, ElementName=templateRoot}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
+            <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=(controls:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
                     <ScrollViewer Margin="0,4" x:Name="DropDownScrollViewer">
                         <controls:SimplePanel RenderOptions.ClearTypeHint="Enabled">
                             <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
@@ -100,6 +100,10 @@
             <Trigger Property="HasItems" Value="false">
                 <Setter Property="Height" TargetName="dropDownBorder" Value="95"/>
             </Trigger>
+            <Trigger Property="controls:DropDownElement.ConsistentWidth" Value="True">
+                <Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
+                <Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
+            </Trigger>
             <MultiTrigger>
                 <MultiTrigger.Conditions>
                     <Condition Property="IsGrouping" Value="true"/>
@@ -145,8 +149,8 @@
                 <TextBlock Margin="1,0,0,0" Text="{Binding Path=(controls:InfoElement.Title),RelativeSource={RelativeSource TemplatedParent}}"/>
                 <ContentPresenter TextElement.Foreground="{DynamicResource DangerBrush}" Margin="4,0,0,0" Content="{Binding Path=(controls:InfoElement.Symbol),RelativeSource={RelativeSource TemplatedParent}}" Visibility="{Binding Path=(controls:InfoElement.Necessary),RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}"/>
             </StackPanel>
-            <Popup Grid.Row="1" Grid.Column="0" x:Name="PART_Popup" 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=(controls:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" MinWidth="{Binding ActualWidth, ElementName=toggleButton}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
+            <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=(controls:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
                     <ScrollViewer Margin="0,4" x:Name="DropDownScrollViewer">
                         <controls:SimplePanel RenderOptions.ClearTypeHint="Enabled">
                             <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
@@ -166,6 +170,10 @@
             <Trigger Property="HasItems" Value="false">
                 <Setter Property="Height" TargetName="dropDownBorder" Value="95"/>
             </Trigger>
+            <Trigger Property="controls:DropDownElement.ConsistentWidth" Value="True">
+                <Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
+                <Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
+            </Trigger>
             <MultiTrigger>
                 <MultiTrigger.Conditions>
                     <Condition Property="IsGrouping" Value="true"/>
@@ -209,8 +217,8 @@
                 <TextBlock Text="{Binding Path=(controls:InfoElement.Title),RelativeSource={RelativeSource TemplatedParent}}"/>
                 <ContentPresenter TextElement.Foreground="{DynamicResource DangerBrush}" Margin="4,0,0,0" Content="{Binding Path=(controls:InfoElement.Symbol),RelativeSource={RelativeSource TemplatedParent}}" Visibility="{Binding Path=(controls:InfoElement.Necessary),RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}"/>
             </StackPanel>
-            <Popup Grid.Column="1" x:Name="PART_Popup" 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=(controls:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" MinWidth="{Binding ActualWidth, ElementName=templateRoot}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
+            <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=(controls:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
                     <ScrollViewer Margin="0,4" x:Name="DropDownScrollViewer">
                         <controls:SimplePanel RenderOptions.ClearTypeHint="Enabled">
                             <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
@@ -230,6 +238,10 @@
             <Trigger Property="HasItems" Value="false">
                 <Setter Property="Height" TargetName="dropDownBorder" Value="95"/>
             </Trigger>
+            <Trigger Property="controls:DropDownElement.ConsistentWidth" Value="True">
+                <Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
+                <Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
+            </Trigger>
             <MultiTrigger>
                 <MultiTrigger.Conditions>
                     <Condition Property="IsGrouping" Value="true"/>
@@ -287,8 +299,8 @@
                 <ColumnDefinition/>
                 <ColumnDefinition Width="30"/>
             </Grid.ColumnDefinitions>
-            <Popup x:Name="PART_Popup" AllowsTransparency="true" Grid.ColumnSpan="2" IsOpen="{Binding IsDropDownOpen, RelativeSource={RelativeSource TemplatedParent}}" PopupAnimation="{StaticResource {x:Static SystemParameters.ComboBoxPopupAnimationKey}}" Placement="Bottom">
-                <Border CornerRadius="{Binding Path=(controls:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" MinWidth="{Binding ActualWidth, ElementName=templateRoot}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
+            <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=(controls:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
                     <ScrollViewer Margin="0,4" x:Name="DropDownScrollViewer">
                         <controls:SimplePanel RenderOptions.ClearTypeHint="Enabled">
                             <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
@@ -308,6 +320,10 @@
             <Trigger Property="HasItems" Value="false">
                 <Setter Property="Height" TargetName="dropDownBorder" Value="95"/>
             </Trigger>
+            <Trigger Property="controls:DropDownElement.ConsistentWidth" Value="True">
+                <Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
+                <Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
+            </Trigger>
             <MultiTrigger>
                 <MultiTrigger.Conditions>
                     <Condition Property="IsGrouping" Value="true"/>
@@ -353,8 +369,8 @@
                 <TextBlock Margin="1,0,0,0" Text="{Binding Path=(controls:InfoElement.Title),RelativeSource={RelativeSource TemplatedParent}}"/>
                 <ContentPresenter TextElement.Foreground="{DynamicResource DangerBrush}" Margin="4,0,0,0" Content="{Binding Path=(controls:InfoElement.Symbol),RelativeSource={RelativeSource TemplatedParent}}" Visibility="{Binding Path=(controls:InfoElement.Necessary),RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}"/>
             </StackPanel>
-            <Popup Grid.Column="0" Grid.Row="1" x:Name="PART_Popup" AllowsTransparency="true" Grid.ColumnSpan="2" IsOpen="{Binding IsDropDownOpen, RelativeSource={RelativeSource TemplatedParent}}" PopupAnimation="{StaticResource {x:Static SystemParameters.ComboBoxPopupAnimationKey}}" Placement="Bottom">
-                <Border CornerRadius="{Binding Path=(controls:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" MinWidth="{Binding ActualWidth, ElementName=templateRoot}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
+            <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=(controls:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
                     <ScrollViewer Margin="0,4" x:Name="DropDownScrollViewer">
                         <controls:SimplePanel RenderOptions.ClearTypeHint="Enabled">
                             <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
@@ -374,6 +390,10 @@
             <Trigger Property="HasItems" Value="false">
                 <Setter Property="Height" TargetName="dropDownBorder" Value="95"/>
             </Trigger>
+            <Trigger Property="controls:DropDownElement.ConsistentWidth" Value="True">
+                <Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
+                <Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
+            </Trigger>
             <MultiTrigger>
                 <MultiTrigger.Conditions>
                     <Condition Property="IsGrouping" Value="true"/>
@@ -417,8 +437,8 @@
                 <TextBlock Text="{Binding Path=(controls:InfoElement.Title),RelativeSource={RelativeSource TemplatedParent}}"/>
                 <ContentPresenter TextElement.Foreground="{DynamicResource DangerBrush}" Margin="4,0,0,0" Content="{Binding Path=(controls:InfoElement.Symbol),RelativeSource={RelativeSource TemplatedParent}}" Visibility="{Binding Path=(controls:InfoElement.Necessary),RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}"/>
             </StackPanel>
-            <Popup Grid.Column="1" x:Name="PART_Popup" AllowsTransparency="true" Grid.ColumnSpan="2" IsOpen="{Binding IsDropDownOpen, RelativeSource={RelativeSource TemplatedParent}}" PopupAnimation="{StaticResource {x:Static SystemParameters.ComboBoxPopupAnimationKey}}" Placement="Bottom">
-                <Border CornerRadius="{Binding Path=(controls:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" MinWidth="{Binding ActualWidth, ElementName=templateRoot}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
+            <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=(controls:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
                     <ScrollViewer Margin="0,4" x:Name="DropDownScrollViewer">
                         <controls:SimplePanel RenderOptions.ClearTypeHint="Enabled">
                             <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
@@ -438,6 +458,10 @@
             <Trigger Property="HasItems" Value="false">
                 <Setter Property="Height" TargetName="dropDownBorder" Value="95"/>
             </Trigger>
+            <Trigger Property="controls:DropDownElement.ConsistentWidth" Value="True">
+                <Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
+                <Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
+            </Trigger>
             <MultiTrigger>
                 <MultiTrigger.Conditions>
                     <Condition Property="IsGrouping" Value="true"/>
@@ -590,8 +614,8 @@
                 <TextBlock Margin="1,0,0,0" Text="{Binding Path=(controls:InfoElement.Title),RelativeSource={RelativeSource TemplatedParent}}"/>
                 <ContentPresenter TextElement.Foreground="{DynamicResource DangerBrush}" Margin="4,0,0,0" Content="{Binding Path=(controls:InfoElement.Symbol),RelativeSource={RelativeSource TemplatedParent}}" Visibility="{Binding Path=(controls:InfoElement.Necessary),RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}"/>
             </StackPanel>
-            <Popup Grid.Row="1" Grid.Column="0" x:Name="PART_Popup" 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=(controls:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" MinWidth="{Binding ActualWidth, ElementName=toggleButton}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
+            <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=(controls:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
                     <ScrollViewer Margin="0,4" x:Name="DropDownScrollViewer">
                         <controls:SimplePanel RenderOptions.ClearTypeHint="Enabled">
                             <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
@@ -613,6 +637,10 @@
             <Trigger Property="HasItems" Value="false">
                 <Setter Property="Height" TargetName="dropDownBorder" Value="95"/>
             </Trigger>
+            <Trigger Property="controls:DropDownElement.ConsistentWidth" Value="True">
+                <Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
+                <Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
+            </Trigger>
             <MultiTrigger>
                 <MultiTrigger.Conditions>
                     <Condition Property="IsGrouping" Value="true"/>
@@ -694,8 +722,8 @@
                 <TextBlock Text="{Binding Path=(controls:InfoElement.Title),RelativeSource={RelativeSource TemplatedParent}}"/>
                 <ContentPresenter TextElement.Foreground="{DynamicResource DangerBrush}" Margin="4,0,0,0" Content="{Binding Path=(controls:InfoElement.Symbol),RelativeSource={RelativeSource TemplatedParent}}" Visibility="{Binding Path=(controls:InfoElement.Necessary),RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}"/>
             </StackPanel>
-            <Popup Grid.Column="1" x:Name="PART_Popup" 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=(controls:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" MinWidth="{Binding ActualWidth, ElementName=templateRoot}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
+            <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=(controls:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
                     <ScrollViewer Margin="0,4" x:Name="DropDownScrollViewer">
                         <controls:SimplePanel RenderOptions.ClearTypeHint="Enabled">
                             <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
@@ -717,6 +745,10 @@
             <Trigger Property="HasItems" Value="false">
                 <Setter Property="Height" TargetName="dropDownBorder" Value="95"/>
             </Trigger>
+            <Trigger Property="controls:DropDownElement.ConsistentWidth" Value="True">
+                <Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
+                <Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
+            </Trigger>
             <MultiTrigger>
                 <MultiTrigger.Conditions>
                     <Condition Property="IsGrouping" Value="true"/>
@@ -801,8 +833,8 @@
                 <TextBlock Margin="1,0,0,0" Text="{Binding Path=(controls:InfoElement.Title),RelativeSource={RelativeSource TemplatedParent}}"/>
                 <ContentPresenter TextElement.Foreground="{DynamicResource DangerBrush}" Margin="4,0,0,0" Content="{Binding Path=(controls:InfoElement.Symbol),RelativeSource={RelativeSource TemplatedParent}}" Visibility="{Binding Path=(controls:InfoElement.Necessary),RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}"/>
             </StackPanel>
-            <Popup Grid.Column="0" Grid.Row="1" x:Name="PART_Popup" AllowsTransparency="true" Grid.ColumnSpan="2" IsOpen="{Binding IsDropDownOpen, RelativeSource={RelativeSource TemplatedParent}}" PopupAnimation="{StaticResource {x:Static SystemParameters.ComboBoxPopupAnimationKey}}" Placement="Bottom">
-                <Border CornerRadius="{Binding Path=(controls:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" MinWidth="{Binding ActualWidth, ElementName=templateRoot}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
+            <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=(controls:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
                     <ScrollViewer Margin="0,4" x:Name="DropDownScrollViewer">
                         <controls:SimplePanel RenderOptions.ClearTypeHint="Enabled">
                             <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
@@ -824,6 +856,10 @@
             <Trigger Property="HasItems" Value="false">
                 <Setter Property="Height" TargetName="dropDownBorder" Value="95"/>
             </Trigger>
+            <Trigger Property="controls:DropDownElement.ConsistentWidth" Value="True">
+                <Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
+                <Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
+            </Trigger>
             <MultiTrigger>
                 <MultiTrigger.Conditions>
                     <Condition Property="IsGrouping" Value="true"/>
@@ -925,8 +961,8 @@
                 <TextBlock Margin="1,0,0,0" Text="{Binding Path=(controls:InfoElement.Title),RelativeSource={RelativeSource TemplatedParent}}"/>
                 <ContentPresenter TextElement.Foreground="{DynamicResource DangerBrush}" Margin="4,0,0,0" Content="{Binding Path=(controls:InfoElement.Symbol),RelativeSource={RelativeSource TemplatedParent}}" Visibility="{Binding Path=(controls:InfoElement.Necessary),RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}"/>
             </StackPanel>
-            <Popup Grid.Column="0" Grid.Row="1" x:Name="PART_Popup" AllowsTransparency="true" Grid.ColumnSpan="2" IsOpen="{Binding IsDropDownOpen, RelativeSource={RelativeSource TemplatedParent}}" PopupAnimation="{StaticResource {x:Static SystemParameters.ComboBoxPopupAnimationKey}}" Placement="Bottom">
-                <Border CornerRadius="{Binding Path=(controls:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" MinWidth="{Binding ActualWidth, ElementName=templateRoot}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
+            <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=(controls:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
                     <ScrollViewer Margin="0,4" x:Name="DropDownScrollViewer">
                         <controls:SimplePanel RenderOptions.ClearTypeHint="Enabled">
                             <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
@@ -937,8 +973,8 @@
                     </ScrollViewer>
                 </Border>
             </Popup>
-            <Popup Grid.Column="0" Grid.Row="1" x:Name="PART_Popup_AutoComplete" StaysOpen="False" AllowsTransparency="true" Grid.ColumnSpan="2" PopupAnimation="{StaticResource {x:Static SystemParameters.ComboBoxPopupAnimationKey}}" Placement="Bottom">
-                <Border CornerRadius="{Binding Path=(controls:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder_AutoComplete" MaxHeight="{TemplateBinding MaxDropDownHeight}" MinWidth="{Binding ActualWidth, ElementName=templateRoot}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
+            <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=(controls:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder_AutoComplete" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
                     <ScrollViewer Margin="0,4" x:Name="DropDownScrollViewer_AutoComplete">
                         <controls:SimplePanel RenderOptions.ClearTypeHint="Enabled">
                             <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
@@ -961,6 +997,12 @@
                 <Setter Property="Height" TargetName="dropDownBorder" Value="95"/>
                 <Setter Property="Height" TargetName="dropDownBorder_AutoComplete" Value="95"/>
             </Trigger>
+            <Trigger Property="controls:DropDownElement.ConsistentWidth" Value="True">
+                <Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
+                <Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
+                <Setter Property="MaxWidth" TargetName="dropDownBorder_AutoComplete" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
+                <Setter Property="MinWidth" TargetName="dropDownBorder_AutoComplete" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
+            </Trigger>
             <MultiTrigger>
                 <MultiTrigger.Conditions>
                     <Condition Property="IsGrouping" Value="true"/>
@@ -1064,8 +1106,8 @@
                 <TextBlock Text="{Binding Path=(controls:InfoElement.Title),RelativeSource={RelativeSource TemplatedParent}}"/>
                 <ContentPresenter TextElement.Foreground="{DynamicResource DangerBrush}" Margin="4,0,0,0" Content="{Binding Path=(controls:InfoElement.Symbol),RelativeSource={RelativeSource TemplatedParent}}" Visibility="{Binding Path=(controls:InfoElement.Necessary),RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}"/>
             </StackPanel>
-            <Popup Grid.Column="1" x:Name="PART_Popup" AllowsTransparency="true" Grid.ColumnSpan="2" IsOpen="{Binding IsDropDownOpen, RelativeSource={RelativeSource TemplatedParent}}" PopupAnimation="{StaticResource {x:Static SystemParameters.ComboBoxPopupAnimationKey}}" Placement="Bottom">
-                <Border CornerRadius="{Binding Path=(controls:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" MinWidth="{Binding ActualWidth, ElementName=templateRoot}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
+            <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=(controls:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
                     <ScrollViewer Margin="0,4" x:Name="DropDownScrollViewer">
                         <controls:SimplePanel RenderOptions.ClearTypeHint="Enabled">
                             <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
@@ -1087,6 +1129,10 @@
             <Trigger Property="HasItems" Value="false">
                 <Setter Property="Height" TargetName="dropDownBorder" Value="95"/>
             </Trigger>
+            <Trigger Property="controls:DropDownElement.ConsistentWidth" Value="True">
+                <Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
+                <Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
+            </Trigger>
             <MultiTrigger>
                 <MultiTrigger.Conditions>
                     <Condition Property="IsGrouping" Value="true"/>
@@ -1185,8 +1231,8 @@
                 <TextBlock Text="{Binding Path=(controls:InfoElement.Title),RelativeSource={RelativeSource TemplatedParent}}"/>
                 <ContentPresenter TextElement.Foreground="{DynamicResource DangerBrush}" Margin="4,0,0,0" Content="{Binding Path=(controls:InfoElement.Symbol),RelativeSource={RelativeSource TemplatedParent}}" Visibility="{Binding Path=(controls:InfoElement.Necessary),RelativeSource={RelativeSource TemplatedParent},Converter={StaticResource Boolean2VisibilityConverter}}"/>
             </StackPanel>
-            <Popup Grid.Column="1" x:Name="PART_Popup" AllowsTransparency="true" Grid.ColumnSpan="2" IsOpen="{Binding IsDropDownOpen, RelativeSource={RelativeSource TemplatedParent}}" PopupAnimation="{StaticResource {x:Static SystemParameters.ComboBoxPopupAnimationKey}}" Placement="Bottom">
-                <Border CornerRadius="{Binding Path=(controls:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" MinWidth="{Binding ActualWidth, ElementName=templateRoot}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
+            <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=(controls:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
                     <ScrollViewer Margin="0,4" x:Name="DropDownScrollViewer">
                         <controls:SimplePanel RenderOptions.ClearTypeHint="Enabled">
                             <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
@@ -1197,8 +1243,8 @@
                     </ScrollViewer>
                 </Border>
             </Popup>
-            <Popup Grid.Column="1" x:Name="PART_Popup_AutoComplete" AllowsTransparency="true" Grid.ColumnSpan="2" PopupAnimation="{StaticResource {x:Static SystemParameters.ComboBoxPopupAnimationKey}}" Placement="Bottom">
-                <Border CornerRadius="{Binding Path=(controls:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder_AutoComplete" MaxHeight="{TemplateBinding MaxDropDownHeight}" MinWidth="{Binding ActualWidth, ElementName=templateRoot}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
+            <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=(controls:BorderElement.CornerRadius),RelativeSource={RelativeSource TemplatedParent}}" x:Name="dropDownBorder_AutoComplete" MaxHeight="{TemplateBinding MaxDropDownHeight}" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" Background="{DynamicResource RegionBrush}">
                     <ScrollViewer Margin="0,4" x:Name="DropDownScrollViewer_AutoComplete">
                         <controls:SimplePanel RenderOptions.ClearTypeHint="Enabled">
                             <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
@@ -1221,6 +1267,12 @@
                 <Setter Property="Height" TargetName="dropDownBorder" Value="95"/>
                 <Setter Property="Height" TargetName="dropDownBorder_AutoComplete" Value="95"/>
             </Trigger>
+            <Trigger Property="controls:DropDownElement.ConsistentWidth" Value="True">
+                <Setter Property="MaxWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
+                <Setter Property="MinWidth" TargetName="dropDownBorder" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
+                <Setter Property="MaxWidth" TargetName="dropDownBorder_AutoComplete" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
+                <Setter Property="MinWidth" TargetName="dropDownBorder_AutoComplete" Value="{Binding ActualWidth, ElementName=toggleButton}"/>
+            </Trigger>
             <MultiTrigger>
                 <MultiTrigger.Conditions>
                     <Condition Property="IsGrouping" Value="true"/>