Dialog: broken focusin event handler when beforeclose event of a modal opens another modal

When opening a modal dialog within the beforeclose event handler of another modal dialog, a stale focusin event handler remains after all dialogs are closed. An error will occur on the first focus event after the dialogs were closed.

The following example was tested in Chromium 23.0.1271.97 and Firefox 18.0.1 and will output an error message to the console:

http://jsfiddle.net/gZETu/6/

While debugging into this, I figured out that the focusin event is obviously registered within the namespace of the first dialog (dialog0). After closing the second dialog, it tries to deregister the focusin event within the wrong namespace, the one of the second dialog (dialog4). This leaves the stale event handler registered.