sourcegit/SourceGit/Resources/Styles/ComboBox.xaml

<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
    <ControlTemplate x:Key="Template.ComboBox.ToggleButton" TargetType="{x:Type ToggleButton}">
        <Grid>
            <Grid.ColumnDefinitions>
                <ColumnDefinition />
                <ColumnDefinition Width="20" />
            </Grid.ColumnDefinitions>
            
            <Border x:Name="Border" Grid.ColumnSpan="2" CornerRadius="0" BorderThickness="{TemplateBinding BorderThickness}" BorderBrush="{DynamicResource Brush.Border1}" Background="Transparent"/>
            <Border Grid.Column="0" CornerRadius="0" Margin="1" Background="Transparent"/>
            <Path x:Name="Arrow" Grid.Column="1" HorizontalAlignment="Center" VerticalAlignment="Center" Data="M 0 0 L 4 4 L 8 0 Z" Fill="{DynamicResource Brush.Border1}"/>
        </Grid>

        <ControlTemplate.Triggers>
            <Trigger Property="IsMouseOver" Value="True">
                <Setter TargetName="Border" Property="BorderBrush" Value="{DynamicResource Brush.Accent1}"/>
            </Trigger>
        </ControlTemplate.Triggers>
    </ControlTemplate>

    <ControlTemplate x:Key="Template.ComboBox.TextBox" TargetType="{x:Type TextBox}">
        <Border x:Name="PART_ContentHost" Focusable="False" Background="{TemplateBinding Background}" />
    </ControlTemplate>

    <Style TargetType="{x:Type ComboBox}">
        <Setter Property="SnapsToDevicePixels" Value="true" />
        <Setter Property="OverridesDefaultStyle" Value="true" />
        <Setter Property="ScrollViewer.HorizontalScrollBarVisibility" Value="Auto" />
        <Setter Property="ScrollViewer.VerticalScrollBarVisibility" Value="Auto" />
        <Setter Property="ScrollViewer.CanContentScroll" Value="true" />
        <Setter Property="BorderThickness" Value="1"/>
        <Setter Property="MinWidth" Value="120" />
        <Setter Property="MinHeight" Value="20" />
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type ComboBox}">
                    <Grid>
                        <ToggleButton x:Name="ToggleButton" BorderThickness="{TemplateBinding BorderThickness}" Template="{StaticResource Template.ComboBox.ToggleButton}" Grid.Column="2" Focusable="false" ClickMode="Press" IsChecked="{Binding IsDropDownOpen, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}"/>
                        <ContentPresenter x:Name="ContentSite" IsHitTestVisible="False" Content="{TemplateBinding SelectionBoxItem}" ContentTemplate="{TemplateBinding SelectionBoxItemTemplate}" ContentTemplateSelector="{TemplateBinding ItemTemplateSelector}" Margin="3,3,23,3" VerticalAlignment="Center" HorizontalAlignment="Left" TextElement.Foreground="{DynamicResource Brush.FG}"/>
                        <TextBox x:Name="PART_EditableTextBox" Style="{x:Null}" Template="{StaticResource Template.ComboBox.TextBox}" HorizontalAlignment="Left" VerticalAlignment="Bottom" Margin="3,3,23,3" Focusable="True" Background="Transparent" Visibility="Hidden" IsReadOnly="{TemplateBinding IsReadOnly}" />
                        <Popup x:Name="Popup" Placement="Bottom" IsOpen="{TemplateBinding IsDropDownOpen}" AllowsTransparency="True" Focusable="False" PopupAnimation="Slide">
                            <Grid x:Name="DropDown" SnapsToDevicePixels="True" MinWidth="{TemplateBinding ActualWidth}" MaxHeight="{TemplateBinding MaxDropDownHeight}">
                                <Border x:Name="DropDownBorder" BorderThickness="1" BorderBrush="{DynamicResource Brush.Border1}" Background="{DynamicResource Brush.BG2}"/>
                                <ScrollViewer Margin="4,6,4,6" SnapsToDevicePixels="True">
                                    <StackPanel IsItemsHost="True" KeyboardNavigation.DirectionalNavigation="Contained" TextElement.Foreground="{DynamicResource Brush.FG}"/>
                                </ScrollViewer>
                            </Grid>
                        </Popup>
                    </Grid>
                    <ControlTemplate.Triggers>
                        <Trigger Property="IsGrouping" Value="true">
                            <Setter Property="ScrollViewer.CanContentScroll" Value="false" />
                        </Trigger>
                        <Trigger SourceName="Popup" Property="AllowsTransparency" Value="true">
                            <Setter TargetName="DropDownBorder" Property="CornerRadius" Value="0" />
                            <Setter TargetName="DropDownBorder" Property="Margin" Value="0,2,0,0" />
                        </Trigger>
                    </ControlTemplate.Triggers>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>

    <Style TargetType="{x:Type ComboBoxItem}">
        <Setter Property="SnapsToDevicePixels" Value="true" />
        <Setter Property="OverridesDefaultStyle" Value="true" />
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type ComboBoxItem}">
                    <Border x:Name="Border" Padding="2" SnapsToDevicePixels="true" Background="Transparent">
                        <ContentPresenter/>
                    </Border>
                    <ControlTemplate.Triggers>
                        <Trigger Property="IsMouseOver" Value="True">
                            <Setter TargetName="Border" Property="Background" Value="{DynamicResource Brush.Accent1}"/>
                        </Trigger>
                    </ControlTemplate.Triggers>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>
</ResourceDictionary>