Sic04/FrameworkLocal/UIClient/Themes/SeaBlue/ContextMenu.xaml

<ResourceDictionary
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d">

    <SolidColorBrush x:Key="ToolBarBackground" Color="WhiteSmoke"/>

    <!--  Separator  -->
	<Style TargetType="{x:Type Separator}">
		<Setter Property="Height" Value="1" />
		<Setter Property="Background" Value="#0f3c5a" />
		<Setter Property="Template">
			<Setter.Value>
				<ControlTemplate TargetType="{x:Type Separator}">
					<Rectangle Height="{TemplateBinding Height}" Fill="White" />
				</ControlTemplate>
			</Setter.Value>
		</Setter>
	</Style>

	<!--  Outer menu items  -->
	<Style TargetType="{x:Type MenuItem}">
		<Setter Property="Background" Value="{StaticResource ToolBarBackground}" />
		<Setter Property="Height" Value="35"/>
		<Setter Property="Foreground" Value="White" />
		<Setter Property="Margin" Value="5"/>
		<Style.Triggers>
			<Trigger Property="IsHighlighted" Value="True">
				<Setter Property="Background" Value="Black" />
			</Trigger>
			<Trigger Property="IsEnabled" Value="False">
				<Setter Property="Foreground" Value="LightGray" />
			</Trigger>
		</Style.Triggers>
	</Style>

	<!--  Outer menu  -->
	<Style TargetType="{x:Type ContextMenu}">
		<Setter Property="OverridesDefaultStyle" Value="True" />
		<Setter Property="SnapsToDevicePixels" Value="True" />
		<Setter Property="Grid.IsSharedSizeScope" Value="true" />
		<Setter Property="HasDropShadow" Value="True" />
		<Setter Property="Template">
			<Setter.Value>
				<ControlTemplate TargetType="{x:Type ContextMenu}">

					<!--  Here is where you change the border thickness to zero on the menu  -->
					<Border
						x:Name="Border"
						BorderThickness="0">
						<StackPanel
							ClipToBounds="True"
							IsItemsHost="True"
							KeyboardNavigation.DirectionalNavigation="Cycle"
							Orientation="Vertical" />
					</Border>
					<ControlTemplate.Triggers>
						<Trigger Property="HasDropShadow" Value="true">
							<Setter TargetName="Border" Property="Padding" Value="0,3,0,3" />
							<Setter TargetName="Border" Property="CornerRadius" Value="4" />
						</Trigger>
						<Trigger Property="IsMouseOver" Value="true">
							<Setter TargetName="Border" Property="Background" Value="{StaticResource ToolBarBackground}" />
						</Trigger>
					</ControlTemplate.Triggers>
				</ControlTemplate>
			</Setter.Value>
		</Setter>
	</Style>

	<!--  SubmenuItem  -->

	<ControlTemplate x:Key="{x:Static MenuItem.SubmenuItemTemplateKey}" TargetType="{x:Type MenuItem}">
		<Border Name="Border">
			<Grid>
				<Grid.ColumnDefinitions>
					<ColumnDefinition Width="Auto" SharedSizeGroup="Icon" />
					<ColumnDefinition Width="*" />
					<ColumnDefinition Width="Auto" SharedSizeGroup="Shortcut" />
					<ColumnDefinition Width="13" />
				</Grid.ColumnDefinitions>
				<ContentPresenter
					Name="Icon"
					Margin="6,0,6,0"
					VerticalAlignment="Center"
					ContentSource="Icon" />
				<Border
					Name="Check"
					Width="13"
					Height="13"
					Margin="6,0,6,0"
					Background="{StaticResource ToolBarBackground}"
					BorderBrush="#5082a4"
					BorderThickness="1"
					Visibility="Collapsed">
					<Path
						Name="CheckMark"
						Width="7"
						Height="7"
						Data="M 0 0 L 7 7 M 0 7 L 7 0"
						SnapsToDevicePixels="False"
						Stroke="#5082a4"
						StrokeThickness="2"
						Visibility="Hidden" />
				</Border>
				<ContentPresenter
					Name="HeaderHost"
					Grid.Column="1"
					ContentSource="Header"
					RecognizesAccessKey="True" />
				<TextBlock
					x:Name="InputGestureText"
					Grid.Column="2"
					Margin="5,2,0,2"
					DockPanel.Dock="Right"
					Text="{TemplateBinding InputGestureText}" />
			</Grid>
		</Border>
		<ControlTemplate.Triggers>
			<Trigger Property="Icon" Value="{x:Null}">
				<Setter TargetName="Icon" Property="Visibility" Value="Hidden" />
			</Trigger>
			<Trigger Property="IsChecked" Value="true">
				<Setter TargetName="CheckMark" Property="Visibility" Value="Visible" />
			</Trigger>
			<Trigger Property="IsCheckable" Value="true">
				<Setter TargetName="Check" Property="Visibility" Value="Visible" />
				<Setter TargetName="Icon" Property="Visibility" Value="Hidden" />
			</Trigger>
			<Trigger Property="IsHighlighted" Value="true">
				<Setter TargetName="Border" Property="Background" Value="#5082a4" />
			</Trigger>
			<Trigger Property="IsEnabled" Value="false">
				<Setter Property="Foreground" Value="#0f3c5a" />
			</Trigger>
		</ControlTemplate.Triggers>
	</ControlTemplate>

	<!--  SubmenuHeader  -->

	<ControlTemplate x:Key="{x:Static MenuItem.SubmenuHeaderTemplateKey}" TargetType="{x:Type MenuItem}">
		<Border Name="Border">
			<Grid>
				<Grid.ColumnDefinitions>
					<ColumnDefinition Width="Auto" SharedSizeGroup="Icon" />
					<ColumnDefinition Width="*" />
					<ColumnDefinition Width="Auto" SharedSizeGroup="Shortcut" />
					<ColumnDefinition Width="13" />
				</Grid.ColumnDefinitions>
				<ContentPresenter
					Name="Icon"
					Margin="6,0,6,0"
					VerticalAlignment="Center"
					ContentSource="Icon" />
				<ContentPresenter
					Name="HeaderHost"
					Grid.Column="1"
					ContentSource="Header"
					RecognizesAccessKey="True" />
				<TextBlock
					x:Name="InputGestureText"
					Grid.Column="2"
					Margin="5,2,2,2"
					DockPanel.Dock="Right"
					Text="{TemplateBinding InputGestureText}" />
				<Path
					Grid.Column="3"
					HorizontalAlignment="Center"
					VerticalAlignment="Center"
					Data="M 0 0 L 0 7 L 4 3.5 Z"
					Fill="#0f3c5a" />
				<Popup
					Name="Popup"
					AllowsTransparency="True"
					Focusable="False"
					HorizontalOffset="-4"
					IsOpen="{TemplateBinding IsSubmenuOpen}"
					Placement="Right"
					PopupAnimation="Fade">
					<Border
						Name="SubmenuBorder"
						Background="{StaticResource ToolBarBackground}"
						BorderBrush="{StaticResource ToolBarBackground}"
						BorderThickness="1"
						SnapsToDevicePixels="True">
						<StackPanel IsItemsHost="True" KeyboardNavigation.DirectionalNavigation="Cycle" />
					</Border>
				</Popup>
			</Grid>
		</Border>

		<ControlTemplate.Triggers>
			<Trigger Property="Icon" Value="{x:Null}">
				<Setter TargetName="Icon" Property="Visibility" Value="Collapsed" />
			</Trigger>
			<Trigger Property="IsHighlighted" Value="true">
				<Setter TargetName="Border" Property="Background" Value="#5082a4" />
			</Trigger>
			<Trigger SourceName="Popup" Property="Popup.AllowsTransparency" Value="True">
				<Setter TargetName="SubmenuBorder" Property="CornerRadius" Value="4" />
				<Setter TargetName="SubmenuBorder" Property="Padding" Value="0,3,0,3" />
			</Trigger>
			<Trigger Property="IsEnabled" Value="false">
				<Setter Property="Foreground" Value="#0f3c5a" />
			</Trigger>
		</ControlTemplate.Triggers>
	</ControlTemplate>
</ResourceDictionary>