How do I remove WPF ComboBox unwanted border around ComboBoxItem area?

Question

I have a ComboBox that has a border around all of the ComboBoxItems as a whole. The picture below shows a white line around the ComboBoxItems in purple. The white line surrounding all of those ComboBoxItems is what I'm trying to remove.

Here is my code.

<ComboBox Name="mycombobox" IsEditable="True" IsReadOnly="True" Text="Test Text" Foreground="Black" BorderThickness="1" BorderBrush="Purple" Background="Yellow" HorizontalAlignment="Left" Width="240" Height="20">

    <ComboBox.ItemContainerStyle>
        <Style TargetType="ComboBoxItem">
            <Setter Property="Background" Value="Purple"/>
            <Setter Property="BorderThickness" Value="0"/>
        </Style> 
    </ComboBox.ItemContainerStyle>
    <ComboBoxItem Name="subItem1">subItem1</ComboBoxItem>
    <ComboBoxItem Name="subItem2">subItem2</ComboBoxItem>
    <ComboBoxItem Name="subItem3">subItem3</ComboBoxItem>
    <ComboBoxItem Name="subItem4">subItem4</ComboBoxItem>
    <ComboBoxItem Name="subItem5">subItem5</ComboBoxItem>
</ComboBox>

I've tried setting border settings in the ItemContainerStyle, but nothing I do removes that border. Any help is appreciated.

Answer 1

You need to edit the Popup border of the ComboBox Control Template. Either by setting the main ComboBox BorderThickness/BorderBrush property as I can see it is template bounded, or by recreating the whole ControlTemplate and having a custom Popup:

Source: MSDN ComboBox Styles And Templates

EDIT

I would HIGHLY recommend using Blend to do this rather than try to recreate the ControlTempalte yourself.

1. Right Click ComboBox -> Edit Template -> Edit A Copy
2. Expand PART_Popup and look for the shadow element and move its child (dropDownBorder) into the shadows parent (PART_Popup)
3. Select dropDownBorder element and choose BorderBrush property and then choose "No Brush"

Without Blend it gets really nasty :|.

This is how it looks:

Here is the code that blend generated (Obviously you would put this into a separate style in a resource dictionary!):

<Window
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:system="clr-namespace:System;assembly=mscorlib"
    xmlns:Themes="clr-namespace:Microsoft.Windows.Themes;assembly=PresentationFramework.Aero2" x:Class="RxUITests.MainWindow"
    Title="MainWindow" Height="350" Width="525">
<Window.Resources>
    <Style x:Key="FocusVisual">
        <Setter Property="Control.Template">
            <Setter.Value>
                <ControlTemplate>
                    <Rectangle Margin="2" SnapsToDevicePixels="true" Stroke="{DynamicResource {x:Static SystemColors.ControlTextBrushKey}}" StrokeThickness="1" StrokeDashArray="1 2"/>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>
    <LinearGradientBrush x:Key="ComboBox.Static.Background" EndPoint="0,1" StartPoint="0,0">
        <GradientStop Color="#FFF0F0F0" Offset="0.0"/>
        <GradientStop Color="#FFE5E5E5" Offset="1.0"/>
    </LinearGradientBrush>
    <SolidColorBrush x:Key="ComboBox.Static.Border" Color="#FFACACAC"/>
    <SolidColorBrush x:Key="ComboBox.Static.Editable.Background" Color="#FFFFFFFF"/>
    <SolidColorBrush x:Key="ComboBox.Static.Editable.Border" Color="#FFABADB3"/>
    <SolidColorBrush x:Key="ComboBox.Static.Editable.Button.Background" Color="Transparent"/>
    <SolidColorBrush x:Key="ComboBox.Static.Editable.Button.Border" Color="Transparent"/>
    <SolidColorBrush x:Key="ComboBox.MouseOver.Glyph" Color="#FF000000"/>
    <LinearGradientBrush x:Key="ComboBox.MouseOver.Background" EndPoint="0,1" StartPoint="0,0">
        <GradientStop Color="#FFECF4FC" Offset="0.0"/>
        <GradientStop Color="#FFDCECFC" Offset="1.0"/>
    </LinearGradientBrush>
    <SolidColorBrush x:Key="ComboBox.MouseOver.Border" Color="#FF7EB4EA"/>
    <SolidColorBrush x:Key="ComboBox.MouseOver.Editable.Background" Color="#FFFFFFFF"/>
    <SolidColorBrush x:Key="ComboBox.MouseOver.Editable.Border" Color="#FF7EB4EA"/>
    <LinearGradientBrush x:Key="ComboBox.MouseOver.Editable.Button.Background" EndPoint="0,1" StartPoint="0,0">
        <GradientStop Color="#FFEBF4FC" Offset="0.0"/>
        <GradientStop Color="#FFDCECFC" Offset="1.0"/>
    </LinearGradientBrush>
    <SolidColorBrush x:Key="ComboBox.MouseOver.Editable.Button.Border" Color="#FF7EB4EA"/>
    <SolidColorBrush x:Key="ComboBox.Pressed.Glyph" Color="#FF000000"/>
    <LinearGradientBrush x:Key="ComboBox.Pressed.Background" EndPoint="0,1" StartPoint="0,0">
        <GradientStop Color="#FFDAECFC" Offset="0.0"/>
        <GradientStop Color="#FFC4E0FC" Offset="1.0"/>
    </LinearGradientBrush>
    <SolidColorBrush x:Key="ComboBox.Pressed.Border" Color="#FF569DE5"/>
    <SolidColorBrush x:Key="ComboBox.Pressed.Editable.Background" Color="#FFFFFFFF"/>
    <SolidColorBrush x:Key="ComboBox.Pressed.Editable.Border" Color="#FF569DE5"/>
    <LinearGradientBrush x:Key="ComboBox.Pressed.Editable.Button.Background" EndPoint="0,1" StartPoint="0,0">
        <GradientStop Color="#FFDAEBFC" Offset="0.0"/>
        <GradientStop Color="#FFC4E0FC" Offset="1.0"/>
    </LinearGradientBrush>
    <SolidColorBrush x:Key="ComboBox.Pressed.Editable.Button.Border" Color="#FF569DE5"/>
    <SolidColorBrush x:Key="ComboBox.Disabled.Glyph" Color="#FFBFBFBF"/>
    <SolidColorBrush x:Key="ComboBox.Disabled.Background" Color="#FFF0F0F0"/>
    <SolidColorBrush x:Key="ComboBox.Disabled.Border" Color="#FFD9D9D9"/>
    <SolidColorBrush x:Key="ComboBox.Disabled.Editable.Background" Color="#FFFFFFFF"/>
    <SolidColorBrush x:Key="ComboBox.Disabled.Editable.Border" Color="#FFBFBFBF"/>
    <SolidColorBrush x:Key="ComboBox.Disabled.Editable.Button.Background" Color="Transparent"/>
    <SolidColorBrush x:Key="ComboBox.Disabled.Editable.Button.Border" Color="Transparent"/>
    <SolidColorBrush x:Key="ComboBox.Static.Glyph" Color="#FF606060"/>
    <Style x:Key="ComboBoxToggleButton" TargetType="{x:Type ToggleButton}">
        <Setter Property="OverridesDefaultStyle" Value="true"/>
        <Setter Property="IsTabStop" Value="false"/>
        <Setter Property="Focusable" Value="false"/>
        <Setter Property="ClickMode" Value="Press"/>
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type ToggleButton}">
                    <Border x:Name="templateRoot" BorderBrush="{StaticResource ComboBox.Static.Border}" BorderThickness="{TemplateBinding BorderThickness}" Background="{StaticResource ComboBox.Static.Background}" SnapsToDevicePixels="true">
                        <Border x:Name="splitBorder" BorderBrush="Transparent" BorderThickness="1" HorizontalAlignment="Right" Margin="0" SnapsToDevicePixels="true" Width="{DynamicResource {x:Static SystemParameters.VerticalScrollBarWidthKey}}">
                            <Path x:Name="arrow" Data="F1 M 0,0 L 2.667,2.66665 L 5.3334,0 L 5.3334,-1.78168 L 2.6667,0.88501 L0,-1.78168 L0,0 Z" Fill="{StaticResource ComboBox.Static.Glyph}" HorizontalAlignment="Center" Margin="0" VerticalAlignment="Center"/>
                        </Border>
                    </Border>
                    <ControlTemplate.Triggers>
                        <MultiDataTrigger>
                            <MultiDataTrigger.Conditions>
                                <Condition Binding="{Binding IsEditable, RelativeSource={RelativeSource AncestorType={x:Type ComboBox}}}" Value="true"/>
                                <Condition Binding="{Binding IsMouseOver, RelativeSource={RelativeSource Self}}" Value="false"/>
                                <Condition Binding="{Binding IsPressed, RelativeSource={RelativeSource Self}}" Value="false"/>
                                <Condition Binding="{Binding IsEnabled, RelativeSource={RelativeSource Self}}" Value="true"/>
                            </MultiDataTrigger.Conditions>
                            <Setter Property="Background" TargetName="templateRoot" Value="{StaticResource ComboBox.Static.Editable.Background}"/>
                            <Setter Property="BorderBrush" TargetName="templateRoot" Value="{StaticResource ComboBox.Static.Editable.Border}"/>
                            <Setter Property="Background" TargetName="splitBorder" Value="{StaticResource ComboBox.Static.Editable.Button.Background}"/>
                            <Setter Property="BorderBrush" TargetName="splitBorder" Value="{StaticResource ComboBox.Static.Editable.Button.Border}"/>
                        </MultiDataTrigger>
                        <Trigger Property="IsMouseOver" Value="true">
                            <Setter Property="Fill" TargetName="arrow" Value="{StaticResource ComboBox.MouseOver.Glyph}"/>
                        </Trigger>
                        <MultiDataTrigger>
                            <MultiDataTrigger.Conditions>
                                <Condition Binding="{Binding IsMouseOver, RelativeSource={RelativeSource Self}}" Value="true"/>
                                <Condition Binding="{Binding IsEditable, RelativeSource={RelativeSource AncestorType={x:Type ComboBox}}}" Value="false"/>
                            </MultiDataTrigger.Conditions>
                            <Setter Property="Background" TargetName="templateRoot" Value="{StaticResource ComboBox.MouseOver.Background}"/>
                            <Setter Property="BorderBrush" TargetName="templateRoot" Value="{StaticResource ComboBox.MouseOver.Border}"/>
                        </MultiDataTrigger>
                        <MultiDataTrigger>
                            <MultiDataTrigger.Conditions>
                                <Condition Binding="{Binding IsMouseOver, RelativeSource={RelativeSource Self}}" Value="true"/>
                                <Condition Binding="{Binding IsEditable, RelativeSource={RelativeSource AncestorType={x:Type ComboBox}}}" Value="true"/>
                            </MultiDataTrigger.Conditions>
                            <Setter Property="Background" TargetName="templateRoot" Value="{StaticResource ComboBox.MouseOver.Editable.Background}"/>
                            <Setter Property="BorderBrush" TargetName="templateRoot" Value="{StaticResource ComboBox.MouseOver.Editable.Border}"/>
                            <Setter Property="Background" TargetName="splitBorder" Value="{StaticResource ComboBox.MouseOver.Editable.Button.Background}"/>
                            <Setter Property="BorderBrush" TargetName="splitBorder" Value="{StaticResource ComboBox.MouseOver.Editable.Button.Border}"/>
                        </MultiDataTrigger>
                        <Trigger Property="IsPressed" Value="true">
                            <Setter Property="Fill" TargetName="arrow" Value="{StaticResource ComboBox.Pressed.Glyph}"/>
                        </Trigger>
                        <MultiDataTrigger>
                            <MultiDataTrigger.Conditions>
                                <Condition Binding="{Binding IsPressed, RelativeSource={RelativeSource Self}}" Value="true"/>
                                <Condition Binding="{Binding IsEditable, RelativeSource={RelativeSource AncestorType={x:Type ComboBox}}}" Value="false"/>
                            </MultiDataTrigger.Conditions>
                            <Setter Property="Background" TargetName="templateRoot" Value="{StaticResource ComboBox.Pressed.Background}"/>
                            <Setter Property="BorderBrush" TargetName="templateRoot" Value="{StaticResource ComboBox.Pressed.Border}"/>
                        </MultiDataTrigger>
                        <MultiDataTrigger>
                            <MultiDataTrigger.Conditions>
                                <Condition Binding="{Binding IsPressed, RelativeSource={RelativeSource Self}}" Value="true"/>
                                <Condition Binding="{Binding IsEditable, RelativeSource={RelativeSource AncestorType={x:Type ComboBox}}}" Value="true"/>
                            </MultiDataTrigger.Conditions>
                            <Setter Property="Background" TargetName="templateRoot" Value="{StaticResource ComboBox.Pressed.Editable.Background}"/>
                            <Setter Property="BorderBrush" TargetName="templateRoot" Value="{StaticResource ComboBox.Pressed.Editable.Border}"/>
                            <Setter Property="Background" TargetName="splitBorder" Value="{StaticResource ComboBox.Pressed.Editable.Button.Background}"/>
                            <Setter Property="BorderBrush" TargetName="splitBorder" Value="{StaticResource ComboBox.Pressed.Editable.Button.Border}"/>
                        </MultiDataTrigger>
                        <Trigger Property="IsEnabled" Value="false">
                            <Setter Property="Fill" TargetName="arrow" Value="{StaticResource ComboBox.Disabled.Glyph}"/>
                        </Trigger>
                        <MultiDataTrigger>
                            <MultiDataTrigger.Conditions>
                                <Condition Binding="{Binding IsEnabled, RelativeSource={RelativeSource Self}}" Value="false"/>
                                <Condition Binding="{Binding IsEditable, RelativeSource={RelativeSource AncestorType={x:Type ComboBox}}}" Value="false"/>
                            </MultiDataTrigger.Conditions>
                            <Setter Property="Background" TargetName="templateRoot" Value="{StaticResource ComboBox.Disabled.Background}"/>
                            <Setter Property="BorderBrush" TargetName="templateRoot" Value="{StaticResource ComboBox.Disabled.Border}"/>
                        </MultiDataTrigger>
                        <MultiDataTrigger>
                            <MultiDataTrigger.Conditions>
                                <Condition Binding="{Binding IsEnabled, RelativeSource={RelativeSource Self}}" Value="false"/>
                                <Condition Binding="{Binding IsEditable, RelativeSource={RelativeSource AncestorType={x:Type ComboBox}}}" Value="true"/>
                            </MultiDataTrigger.Conditions>
                            <Setter Property="Background" TargetName="templateRoot" Value="{StaticResource ComboBox.Disabled.Editable.Background}"/>
                            <Setter Property="BorderBrush" TargetName="templateRoot" Value="{StaticResource ComboBox.Disabled.Editable.Border}"/>
                            <Setter Property="Background" TargetName="splitBorder" Value="{StaticResource ComboBox.Disabled.Editable.Button.Background}"/>
                            <Setter Property="BorderBrush" TargetName="splitBorder" Value="{StaticResource ComboBox.Disabled.Editable.Button.Border}"/>
                        </MultiDataTrigger>
                    </ControlTemplate.Triggers>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>
    <ControlTemplate x:Key="ComboBoxTemplate" TargetType="{x:Type ComboBox}">
        <Grid x:Name="templateRoot" SnapsToDevicePixels="true">
            <Grid.ColumnDefinitions>
                <ColumnDefinition Width="*"/>
                <ColumnDefinition MinWidth="{DynamicResource {x:Static SystemParameters.VerticalScrollBarWidthKey}}" Width="0"/>
            </Grid.ColumnDefinitions>
            <Popup x:Name="PART_Popup" AllowsTransparency="true" Grid.ColumnSpan="2" IsOpen="{Binding IsDropDownOpen, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}" Margin="1" PopupAnimation="{DynamicResource {x:Static SystemParameters.ComboBoxPopupAnimationKey}}" Placement="Bottom">
                        <ScrollViewer x:Name="DropDownScrollViewer">
                            <Grid x:Name="grid" RenderOptions.ClearTypeHint="Enabled">
                                <Canvas x:Name="canvas" HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
                                    <Rectangle x:Name="opaqueRect" Fill="{Binding Background, ElementName=dropDownBorder}" Height="{Binding ActualHeight, ElementName=dropDownBorder}" Width="{Binding ActualWidth, ElementName=dropDownBorder}"/>
                                </Canvas>
                                <ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
                            </Grid>
                        </ScrollViewer>
            </Popup>
            <ToggleButton x:Name="toggleButton" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="{TemplateBinding Background}" Grid.ColumnSpan="2" IsChecked="{Binding IsDropDownOpen, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}" Style="{StaticResource ComboBoxToggleButton}"/>
            <ContentPresenter x:Name="contentPresenter" ContentTemplate="{TemplateBinding SelectionBoxItemTemplate}" ContentTemplateSelector="{TemplateBinding ItemTemplateSelector}" Content="{TemplateBinding SelectionBoxItem}" ContentStringFormat="{TemplateBinding SelectionBoxItemStringFormat}" HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" IsHitTestVisible="false" Margin="{TemplateBinding Padding}" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" VerticalAlignment="{TemplateBinding VerticalContentAlignment}"/>
        </Grid>
        <ControlTemplate.Triggers>
            <Trigger Property="HasItems" Value="false">
                <Setter Property="Height"
                        TargetName="DropDownScrollViewer" Value="95"/>
            </Trigger>
            <MultiTrigger>
                <MultiTrigger.Conditions>
                    <Condition Property="IsGrouping" Value="true"/>
                    <Condition Property="VirtualizingPanel.IsVirtualizingWhenGrouping" Value="false"/>
                </MultiTrigger.Conditions>
                <Setter Property="ScrollViewer.CanContentScroll" Value="false"/>
            </MultiTrigger>
            <Trigger Property="ScrollViewer.CanContentScroll" SourceName="DropDownScrollViewer" Value="false">
                <Setter Property="Canvas.Top" TargetName="opaqueRect" Value="{Binding VerticalOffset, ElementName=DropDownScrollViewer}"/>
                <Setter Property="Canvas.Left" TargetName="opaqueRect" Value="{Binding HorizontalOffset, ElementName=DropDownScrollViewer}"/>
            </Trigger>
        </ControlTemplate.Triggers>
    </ControlTemplate>
    <SolidColorBrush x:Key="TextBox.Static.Background" Color="#FFFFFFFF"/>
    <Style x:Key="ComboBoxEditableTextBox" TargetType="{x:Type TextBox}">
        <Setter Property="OverridesDefaultStyle" Value="true"/>
        <Setter Property="AllowDrop" Value="true"/>
        <Setter Property="MinWidth" Value="0"/>
        <Setter Property="MinHeight" Value="0"/>
        <Setter Property="FocusVisualStyle" Value="{x:Null}"/>
        <Setter Property="ScrollViewer.PanningMode" Value="VerticalFirst"/>
        <Setter Property="Stylus.IsFlicksEnabled" Value="False"/>
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type TextBox}">
                    <ScrollViewer x:Name="PART_ContentHost" Background="Transparent" Focusable="false" HorizontalScrollBarVisibility="Hidden" VerticalScrollBarVisibility="Hidden"/>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>
    <ControlTemplate x:Key="ComboBoxEditableTemplate" TargetType="{x:Type ComboBox}">
        <Grid x:Name="templateRoot" SnapsToDevicePixels="true">
            <Grid.ColumnDefinitions>
                <ColumnDefinition Width="*"/>
                <ColumnDefinition MinWidth="{DynamicResource {x:Static SystemParameters.VerticalScrollBarWidthKey}}" Width="0"/>
            </Grid.ColumnDefinitions>
            <Popup x:Name="PART_Popup" AllowsTransparency="true" Grid.ColumnSpan="2" IsOpen="{Binding IsDropDownOpen, RelativeSource={RelativeSource TemplatedParent}}" PopupAnimation="{DynamicResource {x:Static SystemParameters.ComboBoxPopupAnimationKey}}" Placement="Bottom">
                <Border x:Name="dropDownBorder" BorderBrush="{x:Null}" BorderThickness="1" Background="{DynamicResource {x:Static SystemColors.WindowBrushKey}}">
                    <ScrollViewer x:Name="DropDownScrollViewer">
                        <Grid x:Name="grid" RenderOptions.ClearTypeHint="Enabled">
                            <Canvas x:Name="canvas" HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
                                <Rectangle x:Name="opaqueRect" Fill="{Binding Background, ElementName=dropDownBorder}" Height="{Binding ActualHeight, ElementName=dropDownBorder}" Width="{Binding ActualWidth, ElementName=dropDownBorder}"/>
                            </Canvas>
                            <ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
                        </Grid>
                    </ScrollViewer>
                </Border>
            </Popup>
            <ToggleButton x:Name="toggleButton" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="{TemplateBinding Background}" Grid.ColumnSpan="2" IsChecked="{Binding IsDropDownOpen, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}" Style="{StaticResource ComboBoxToggleButton}"/>
            <Border x:Name="border" Background="{StaticResource TextBox.Static.Background}" Margin="{TemplateBinding BorderThickness}">
                <TextBox x:Name="PART_EditableTextBox" HorizontalContentAlignment="{TemplateBinding HorizontalContentAlignment}" IsReadOnly="{Binding IsReadOnly, RelativeSource={RelativeSource TemplatedParent}}" Margin="{TemplateBinding Padding}" Style="{StaticResource ComboBoxEditableTextBox}" VerticalContentAlignment="{TemplateBinding VerticalContentAlignment}"/>
            </Border>
        </Grid>
        <ControlTemplate.Triggers>
            <Trigger Property="IsEnabled" Value="false">
                <Setter Property="Opacity" TargetName="border" Value="0.56"/>
            </Trigger>
            <Trigger Property="IsKeyboardFocusWithin" Value="true">
                <Setter Property="Foreground" Value="Black"/>
            </Trigger>
            <Trigger Property="HasDropShadow" SourceName="PART_Popup" Value="true"/>
            <Trigger Property="HasItems" Value="false">
                <Setter Property="Height" TargetName="dropDownBorder" Value="95"/>
            </Trigger>
            <MultiTrigger>
                <MultiTrigger.Conditions>
                    <Condition Property="IsGrouping" Value="true"/>
                    <Condition Property="VirtualizingPanel.IsVirtualizingWhenGrouping" Value="false"/>
                </MultiTrigger.Conditions>
                <Setter Property="ScrollViewer.CanContentScroll" Value="false"/>
            </MultiTrigger>
            <Trigger Property="ScrollViewer.CanContentScroll" SourceName="DropDownScrollViewer" Value="false">
                <Setter Property="Canvas.Top" TargetName="opaqueRect" Value="{Binding VerticalOffset, ElementName=DropDownScrollViewer}"/>
                <Setter Property="Canvas.Left" TargetName="opaqueRect" Value="{Binding HorizontalOffset, ElementName=DropDownScrollViewer}"/>
            </Trigger>
        </ControlTemplate.Triggers>
    </ControlTemplate>
    <Style x:Key="ComboBoxStyle1" TargetType="{x:Type ComboBox}">
        <Setter Property="FocusVisualStyle" Value="{StaticResource FocusVisual}"/>
        <Setter Property="Background" Value="{StaticResource ComboBox.Static.Background}"/>
        <Setter Property="BorderBrush" Value="{StaticResource ComboBox.Static.Border}"/>
        <Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.WindowTextBrushKey}}"/>
        <Setter Property="BorderThickness" Value="1"/>
        <Setter Property="ScrollViewer.HorizontalScrollBarVisibility" Value="Auto"/>
        <Setter Property="ScrollViewer.VerticalScrollBarVisibility" Value="Auto"/>
        <Setter Property="Padding" Value="6,3,5,3"/>
        <Setter Property="ScrollViewer.CanContentScroll" Value="true"/>
        <Setter Property="ScrollViewer.PanningMode" Value="Both"/>
        <Setter Property="Stylus.IsFlicksEnabled" Value="False"/>
        <Setter Property="Template" Value="{StaticResource ComboBoxTemplate}"/>
        <Style.Triggers>
            <Trigger Property="IsEditable" Value="true">
                <Setter Property="IsTabStop" Value="false"/>
                <Setter Property="Padding" Value="2"/>
                <Setter Property="Template" Value="{StaticResource ComboBoxEditableTemplate}"/>
            </Trigger>
        </Style.Triggers>
    </Style>
</Window.Resources>
<Grid>
    <ComboBox x:Name="Mycombobox"
        IsEditable="True"
        IsReadOnly="True"
        Text="Test Text"
        Foreground="Black"
        BorderThickness="1"
        BorderBrush="Purple"
        Background="Yellow"
        HorizontalAlignment="Left"
        Width="240"
        Height="20" Style="{DynamicResource ComboBoxStyle1}">

        <ComboBoxItem x:Name="SubItem1" Content="subItem1"/>
        <ComboBoxItem x:Name="SubItem2" Content="subItem2"/>
        <ComboBoxItem x:Name="SubItem3" Content="subItem3"/>
        <ComboBoxItem x:Name="SubItem4" Content="subItem4"/>
        <ComboBoxItem x:Name="SubItem5" Content="subItem5"/>
    </ComboBox>
</Grid>