This menuItem because it's linked to a command does the magic behind the scenes for me:
<MenuItem Name="mnuOpen" Command="Open"/>
where I have
<Window.CommandBindings>
<CommandBinding Command="Open"
Executed="CommandBinding_Open_Executed"
CanExecute="CommandBinding_ProjectSelected"/>
</Window.CommandBindings>
but every binding I've tried has failed to do anything.
<MenuItem Name="mnuExplorer" Click="mnuExplorer_Click" Header="Open Containing Folder" IsEnabled="{Binding ElementName=mnuOpen, Path=IsEnabled}" />