wpf-visual-process-framework/VisionFrame/Assets/Styles/ComboBoxStyles.xaml

<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">


    <SolidColorBrush x:Key="TextBox.Static.Background" Color="#FFFFFFFF"/>
    <SolidColorBrush x:Key="ComboBox.Static.Border" Color="#FFACACAC"/>
    <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"
                                Background="{TemplateBinding Background}" 
                                BorderThickness="{TemplateBinding BorderThickness}" 
                                BorderBrush="#DDDDDD"
                                CornerRadius="3">
                        <Border x:Name="splitBorder" Width="{DynamicResource {x:Static SystemParameters.VerticalScrollBarWidthKey}}" 
                                    SnapsToDevicePixels="true" Margin="0" HorizontalAlignment="Right" 
                                    BorderThickness="1" BorderBrush="Transparent">
                            <Path Data="M0 0 4 4 8 0" Stroke="#CCC" StrokeThickness="1"
                                   VerticalAlignment="Center" Name="path"
                                  Width="8" HorizontalAlignment="Center"
                                  RenderTransformOrigin="0.5,0.5"/>
                        </Border>
                    </Border>
                    <ControlTemplate.Triggers>
                        <Trigger Property="IsMouseOver" Value="true">
                            <Setter Property="BorderBrush" TargetName="templateRoot" Value="green"/>
                        </Trigger>
                        <Trigger Property="IsKeyboardFocused" Value="true">
                            <Setter Property="BorderBrush" TargetName="templateRoot" Value="green"/>
                        </Trigger>
                        <Trigger Property="IsChecked" Value="True">
                            <Setter TargetName="path" Property="RenderTransform">
                                <Setter.Value>
                                    <RotateTransform Angle="180"/>
                                </Setter.Value>
                            </Setter>
                        </Trigger>
                    </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" VerticalOffset="1">
                <Border x:Name="dropDownBorder" 
                                BorderBrush="#DDD" 
                                BorderThickness="1" CornerRadius="5"
                                Background="{DynamicResource {x:Static SystemColors.WindowBrushKey}}"
                        MaxHeight="{TemplateBinding MaxDropDownHeight}" 
                        MinWidth="{Binding ActualWidth, ElementName=templateRoot}">
                    <ScrollViewer x:Name="DropDownScrollViewer" 
                                  Background="Transparent" BorderThickness="0">
                        <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}"
                                               RadiusX="7" RadiusY="7"/>
                            </Canvas>
                            <ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" 
                                                SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"
                                                Margin="3"/>
                        </Grid>
                    </ScrollViewer>
                </Border>
            </Popup>
            <ToggleButton x:Name="toggleButton" BorderBrush="{TemplateBinding BorderBrush}" 
                              BorderThickness="{TemplateBinding BorderThickness}" 
                              Background="White" 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="HasDropShadow" SourceName="PART_Popup" Value="true">
                <Setter Property="Margin" TargetName="shadow" Value="0,0,5,5"/>
                <Setter Property="Background" TargetName="shadow" Value="#71000000"/>
            </Trigger>-->
            <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 TargetType="{x:Type ComboBox}">
        <Setter Property="Background" Value="White"/>
        <Setter Property="Foreground" Value="#333"/>
        <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="VerticalContentAlignment" Value="Center"/>
        <Setter Property="Template" Value="{StaticResource ComboBoxTemplate}"/>
    </Style>

    <Style TargetType="ComboBoxItem">
        <Setter Property="Height" Value="30"/>
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="ComboBoxItem">
                    <Border Background="White" BorderBrush="Transparent" BorderThickness="1" CornerRadius="3"
                            Margin="1" Name="border">
                        <ContentPresenter VerticalAlignment="Center" Margin="3"/>
                    </Border>
                    <ControlTemplate.Triggers>
                        <Trigger Property="IsMouseOver" Value="True">
                            <Setter TargetName="border" Property="Background" Value="#111F71E5"/>
                            <Setter TargetName="border" Property="BorderBrush" Value="#551F71E5"/>
                        </Trigger>
                        <Trigger Property="IsSelected" Value="True">
                            <Setter TargetName="border" Property="Background" Value="#1F71E5"/>
                            <Setter TargetName="border" Property="BorderBrush" Value="#1F71E5"/>
                            <Setter Property="Foreground" Value="White"/>
                        </Trigger>
                    </ControlTemplate.Triggers>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>
</ResourceDictionary>