[Udo]

I agree with you on that. The primary usage mode for these buttons are probably AJAX forms, and those can be very frustrating for lots of reasons. I think it's great to have some kind of visual feedback that you're action is being performed, but at the same time transmissions errors should not result in a stuck app. That's why I think the UI practice suggested by these buttons is likely to result in user frustration, but still there is no additional usability loss when removing the focus from an already disabled button.