Separator element in XAML adds a separator to a ContextMenu.
This code snippet creates a ContextMenu with a separator.
<ContextMenu Name="RectangleMenu">
<MenuItem Header="Color">
<MenuItem Header="Red" Click="RedMenuItem_Click" />
<Separator />
<MenuItem Header="Green" Click="GreenMenuItem_Click"/>
<MenuItem Header="Orange" Click="OrangeMenuItem_Click"/>
</MenuItem>
</ContextMenu>