Comment 56 for bug 187313

Umang, what you wrote is a real find and I'm surprised there's so little
followup.

I could almost repeat almost what you described.
I would phrase it as follows.

If a context menu is canceled, a right-click in the area from which it
disappeared may produce the action that would have been taken if the
menu was still there.

I wrote "almost", "canceled" and "may" because
- Warning, I couldn't get it work all the time, sometimes easily
sometimes with difficulty
- Any possible way to have the menu disappear works (right-click, escape
...)

But I sure produced what you say more than enough to be convinced that
it's at least closely related to this bug.
I even wonder if I didn't watch the same events outside FireFox (Xopen
bug?).

On a very slow system, it's even trickier to watch because, although the
system behaves as if it did, the context menu may not appear and you
think you just clicked twice.
So that you right-click, you wait, it misbehaves and you're under the
impression that the problem is related to this single click but, in
fact, you clicked in a menu that never showed up produced by another
click that occurred an amazing number of CPU cycles ago.