I have a user request to add an accelerator to a sub menu (JMenu) which would allow the user to press the short cut and have the corresponding sub menu "fold out", showing its contained menu items.

I don't recall every having seen something like this (either in Java or any other language). Our application is written in Java using Swing. We have a number of JMenuItems with accelerators that work well, but when I attempted to add an accelerator to JMenu I get the following exception:

java.lang.Error: setAccelerator() is not defined for JMenu. Use setMnemonic() instead.

I've tried to use the [MenuDemo](http://docs.oracle.com/javase/tutorial/uiswing/examples/components/MenuDemoProject/src/components/MenuDemo.java)! code to experiment with this a bit further.

This is what I tried:

```
//a submenu
menu.addSeparator();
submenu = new JMenu("A submenu");
submenu.setMnemonic(KeyEvent.VK_S);
submenu.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_U, InputEvent.CTRL_MASK));

```

The last line is the one added by me, which causes the exception.

I've tried extensive googling but all I can find is articles on how to add accelerators to JMenuItem.

It seems the JMenu does not support this natively. Is there any workaround to achieve this behaviour?