See  http://jsbin.com/ijovi/3

The behavior with FF 3.5.8 when doubleclicking a checkbox is to stop changing the checked state once after one click.  It does not continue changing state while rapidly clicking or double clicking.  In Chrome continuous clicks continuously toggle the checkbox state.

However the UI Button does continue changing its active state regardless of its inputs checked state.

Also, I may be misunderstanding things, but the aria-pressed state seems to be exactly opposite of the inputs checked state.  I see this behavior on both FF and Chrome.

I tried writing a patch which appears to fix the problem and the proper log output appears, however the UI can still becomes out of sync with the right combination of fast clicks.