<Menu.CommandBindings>
<CommandBinding Command="Copy" CanExecute="CommandBinding_OnCanExecute"></CommandBinding>
</Menu.CommandBindings>
<MenuItem Header="Edit" >
<MenuItem Header="Copy" Command="Copy"></MenuItem>
</MenuItem>private void CommandBinding_OnCanExecute(object sender, CanExecuteRoutedEventArgs e)
{
e.CanExecute = false;
e.Handled = true;
}