combo template resources.xaml

<Window.Resources>
		<Style x:Key="ComboBoxFocusVisual">
			<Setter Property="Control.Template">
				<Setter.Value>
					<ControlTemplate>
						<Rectangle Margin="4,4,21,4" SnapsToDevicePixels="true" Stroke="{DynamicResource {x:Static SystemColors.ControlTextBrushKey}}" StrokeThickness="1" StrokeDashArray="1 2"/>
					</ControlTemplate>
				</Setter.Value>
			</Setter>
		</Style>
		<LinearGradientBrush x:Key="ButtonNormalBackground" EndPoint="0,1" StartPoint="0,0">
			<GradientStop Color="#F3F3F3" Offset="0"/>
			<GradientStop Color="#EBEBEB" Offset="0.5"/>
			<GradientStop Color="#DDDDDD" Offset="0.5"/>
			<GradientStop Color="#CDCDCD" Offset="1"/>
		</LinearGradientBrush>
		<SolidColorBrush x:Key="ButtonNormalBorder" Color="#FF707070"/>
		<Geometry x:Key="DownArrowGeometry">M 0 0 L 3.5 4 L 7 0 Z</Geometry>
		<Style x:Key="ComboBoxReadonlyToggleButton" 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}">
						<Microsoft_Windows_Themes:ButtonChrome x:Name="Chrome" BorderBrush="{TemplateBinding BorderBrush}" Background="{TemplateBinding Background}" RenderMouseOver="{TemplateBinding IsMouseOver}" RenderPressed="{TemplateBinding IsPressed}" SnapsToDevicePixels="true">
							<Grid HorizontalAlignment="Right" Width="{DynamicResource {x:Static SystemParameters.VerticalScrollBarWidthKey}}">
								<Path x:Name="Arrow" Data="{StaticResource DownArrowGeometry}" Fill="Black" HorizontalAlignment="Center" Margin="3,1,0,0" VerticalAlignment="Center"/>
							</Grid>
						</Microsoft_Windows_Themes:ButtonChrome>
						<ControlTemplate.Triggers>
							<Trigger Property="IsChecked" Value="true">
								<Setter Property="RenderPressed" TargetName="Chrome" Value="true"/>
							</Trigger>
							<Trigger Property="IsEnabled" Value="false">
								<Setter Property="Fill" TargetName="Arrow" Value="#AFAFAF"/>
							</Trigger>
						</ControlTemplate.Triggers>
					</ControlTemplate>
				</Setter.Value>
			</Setter>
		</Style>
		<LinearGradientBrush x:Key="TextBoxBorder" EndPoint="0,20" MappingMode="Absolute" StartPoint="0,0">
			<GradientStop Color="#ABADB3" Offset="0.05"/>
			<GradientStop Color="#E2E3EA" Offset="0.07"/>
			<GradientStop Color="#E3E9EF" Offset="1"/>
		</LinearGradientBrush>
		<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>
		<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}">
						<Microsoft_Windows_Themes:ButtonChrome x:Name="Chrome" BorderBrush="{TemplateBinding BorderBrush}" Background="{TemplateBinding Background}" RenderMouseOver="{TemplateBinding IsMouseOver}" RenderPressed="{TemplateBinding IsPressed}" RoundCorners="false" SnapsToDevicePixels="true" Width="{DynamicResource {x:Static SystemParameters.VerticalScrollBarWidthKey}}">
							<Path x:Name="Arrow" Data="{StaticResource DownArrowGeometry}" Fill="Black" HorizontalAlignment="Center" Margin="0,1,0,0" VerticalAlignment="Center"/>
						</Microsoft_Windows_Themes:ButtonChrome>
						<ControlTemplate.Triggers>
							<Trigger Property="IsChecked" Value="true">
								<Setter Property="RenderPressed" TargetName="Chrome" Value="true"/>
							</Trigger>
							<Trigger Property="IsEnabled" Value="false">
								<Setter Property="Fill" TargetName="Arrow" Value="#AFAFAF"/>
							</Trigger>
						</ControlTemplate.Triggers>
					</ControlTemplate>
				</Setter.Value>
			</Setter>
		</Style>
		<ControlTemplate x:Key="ComboBoxEditableTemplate" TargetType="{x:Type ComboBox}">
			<Grid x:Name="Placement" SnapsToDevicePixels="true">
				<Grid.ColumnDefinitions>
					<ColumnDefinition Width="*"/>
					<ColumnDefinition Width="Auto"/>
				</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">
					<Microsoft_Windows_Themes:SystemDropShadowChrome x:Name="Shdw" Color="Transparent" MaxHeight="{TemplateBinding MaxDropDownHeight}" MinWidth="{Binding ActualWidth, ElementName=Placement}">
						<Border x:Name="DropDownBorder" BorderBrush="{DynamicResource {x:Static SystemColors.WindowFrameBrushKey}}" BorderThickness="1" Background="{DynamicResource {x:Static SystemColors.WindowBrushKey}}">
							<ScrollViewer x:Name="DropDownScrollViewer">
								<Grid RenderOptions.ClearTypeHint="Enabled">
									<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>
					</Microsoft_Windows_Themes:SystemDropShadowChrome>
				</Popup>
				<Microsoft_Windows_Themes:ListBoxChrome x:Name="Border" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="{TemplateBinding Background}" Grid.ColumnSpan="2" RenderMouseOver="{TemplateBinding IsMouseOver}" RenderFocused="{TemplateBinding IsKeyboardFocusWithin}"/>
				<TextBox x:Name="PART_EditableTextBox" HorizontalContentAlignment="{TemplateBinding HorizontalContentAlignment}" IsReadOnly="{Binding IsReadOnly, RelativeSource={RelativeSource TemplatedParent}}" Margin="{TemplateBinding Padding}" Style="{StaticResource ComboBoxEditableTextBox}" VerticalContentAlignment="{TemplateBinding VerticalContentAlignment}"/>
				<ToggleButton Grid.Column="1" IsChecked="{Binding IsDropDownOpen, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}" Style="{StaticResource ComboBoxToggleButton}"/>
			</Grid>
			<ControlTemplate.Triggers>
				<Trigger Property="IsKeyboardFocusWithin" Value="true">
					<Setter Property="Foreground" Value="Black"/>
				</Trigger>
				<Trigger Property="IsDropDownOpen" Value="true">
					<Setter Property="RenderFocused" TargetName="Border" Value="true"/>
				</Trigger>
				<Trigger Property="HasItems" Value="false">
					<Setter Property="Height" TargetName="DropDownBorder" Value="95"/>
				</Trigger>
				<Trigger Property="IsEnabled" Value="false">
					<Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.GrayTextBrushKey}}"/>
					<Setter Property="Background" Value="#FFF4F4F4"/>
				</Trigger>
				<Trigger Property="IsGrouping" Value="true">
					<Setter Property="ScrollViewer.CanContentScroll" Value="false"/>
				</Trigger>
				<Trigger Property="HasDropShadow" SourceName="PART_Popup" Value="true">
					<Setter Property="Margin" TargetName="Shdw" Value="0,0,5,5"/>
					<Setter Property="Color" TargetName="Shdw" Value="#71000000"/>
				</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}"/>
				</Trigger>
			</ControlTemplate.Triggers>
		</ControlTemplate>
		<Style x:Key="ComboBoxStyle1" TargetType="{x:Type ComboBox}">
			<Setter Property="FocusVisualStyle" Value="{StaticResource ComboBoxFocusVisual}"/>
			<Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.WindowTextBrushKey}}"/>
			<Setter Property="Background" Value="{StaticResource ButtonNormalBackground}"/>
			<Setter Property="BorderBrush" Value="{StaticResource ButtonNormalBorder}"/>
			<Setter Property="BorderThickness" Value="1"/>
			<Setter Property="ScrollViewer.HorizontalScrollBarVisibility" Value="Auto"/>
			<Setter Property="ScrollViewer.VerticalScrollBarVisibility" Value="Auto"/>
			<Setter Property="Padding" Value="4,3"/>
			<Setter Property="ScrollViewer.CanContentScroll" Value="true"/>
			<Setter Property="ScrollViewer.PanningMode" Value="Both"/>
			<Setter Property="Stylus.IsFlicksEnabled" Value="False"/>
			<Setter Property="Template">
				<Setter.Value>
					<ControlTemplate TargetType="{x:Type ComboBox}">
						<Grid x:Name="MainGrid" 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}}" Margin="1" PopupAnimation="{DynamicResource {x:Static SystemParameters.ComboBoxPopupAnimationKey}}" Placement="Bottom">
								<Microsoft_Windows_Themes:SystemDropShadowChrome x:Name="Shdw" Color="Transparent" MaxHeight="{TemplateBinding MaxDropDownHeight}" MinWidth="{Binding ActualWidth, ElementName=MainGrid}">
									<Border x:Name="DropDownBorder" BorderBrush="{DynamicResource {x:Static SystemColors.WindowFrameBrushKey}}" BorderThickness="1" Background="{DynamicResource {x:Static SystemColors.WindowBrushKey}}">
										<ScrollViewer x:Name="DropDownScrollViewer">
											<Grid RenderOptions.ClearTypeHint="Enabled">
												<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>
								</Microsoft_Windows_Themes:SystemDropShadowChrome>
							</Popup>
							<ToggleButton BorderBrush="{TemplateBinding BorderBrush}" Background="{TemplateBinding Background}" Grid.ColumnSpan="2" IsChecked="{Binding IsDropDownOpen, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}" Style="{StaticResource ComboBoxReadonlyToggleButton}"/>
							<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="Shdw" Value="0,0,5,5"/>
								<Setter Property="Color" TargetName="Shdw" Value="#71000000"/>
							</Trigger>
							<Trigger Property="HasItems" Value="false">
								<Setter Property="Height" TargetName="DropDownBorder" Value="95"/>
							</Trigger>
							<Trigger Property="IsEnabled" Value="false">
								<Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.GrayTextBrushKey}}"/>
								<Setter Property="Background" Value="#FFF4F4F4"/>
							</Trigger>
							<Trigger Property="IsGrouping" Value="true">
								<Setter Property="ScrollViewer.CanContentScroll" Value="false"/>
							</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}"/>
							</Trigger>
						</ControlTemplate.Triggers>
					</ControlTemplate>
				</Setter.Value>
			</Setter>
			<Style.Triggers>
				<Trigger Property="IsEditable" Value="true">
					<Setter Property="BorderBrush" Value="{StaticResource TextBoxBorder}"/>
					<Setter Property="Background" Value="{DynamicResource {x:Static SystemColors.WindowBrushKey}}"/>
					<Setter Property="IsTabStop" Value="false"/>
					<Setter Property="Padding" Value="3"/>
					<Setter Property="Template" Value="{StaticResource ComboBoxEditableTemplate}"/>
				</Trigger>
			</Style.Triggers>
		</Style>
	</Window.Resources>