public void keyPressed(KeyEvent e) {
                if (e.isControlDown()) {
					if ('Z' == e.getKeyCode()) {
						if (undoManager.canUndo()) {
							undoManager.undo();
						}
					} else if ('Y' == e.getKeyCode()) {
						if (undoManager.canRedo()) {
							undoManager.redo();
						}
					}
				}
			}