public void doCommand( final Command command ) {
		final boolean changed = command.perform();

		System.out.println( "CommandControl.doCommand(): " + command.getClass() + "  " + changed );

		if( changed && command instanceof UndoableCommand ) {
			final boolean oldCanUndo = canUndo();
			undoStack.add( (UndoableCommand) command );
			if( canUndo() != oldCanUndo ) {
				informCanUndoRedoListeners();
			}
			System.out.println( "CommandControl.doCommand(): undoStackSize=" + undoStack.size() );
		}
	}