You can be tricked into resigning

[Pizzaelemblast]

If you request an undo, the opponent can say "brb" and then disappear a while. Then it allows him to force you to resign, as if YOU were the idle one... even though it's waiting on him to either deny or grant your undo request.

Looking at you, MrDemon77.

[jsh]

It's like this to prevent abuse, actually. Someone could repeatedly request undos and run the clock.

[Pizzaelemblast]

I don't see how that's possible. You just press deny.

[Pizzaelemblast]

If someone got annoyed that you were denying their undo request, they could still idle to be a nuisance in game just as easily, waiting a long minute before each click. Someone did this to me once.

[Pizzaelemblast]

But I guess with the undo button someone could (very theoretically) just continue clicking it infinitely without inevitable game progess. I think the true solution would be to make it so after deny has been pressed, the undo button can't pressed again until something else happens.