@CanExecute
public boolean canExecute( ESelectionService selectionService, MPart part, MItem item )
{
    boolean canExecute = false;

    //...Custom code here to test enablement/executability...
		
    //The addition: if a menuitem, make it invisible if not executable. (I use the same handler for toolitem, hence the instanceof-test)
   if ( item instanceof MMenuItem ) {
       item.setVisible( canExecute );
   }
   return canExecute;
}