I saw something recently, and I found it quite annoying :P.
I asked a question, and chose to upvote an answer that I recieved about 5 minutes after I posted the question
However, after clicking the button, I got a popup saying something like this:
Accept the answer if you found it helpful. This is not exactly what it said, but it is similar.
But then I realised that I could not accept the answer, as I must accept after 20 minutes.
My point is that the Popup shows saying accept, when I can't accept it, and is this a bug or bad feature design, and I think it should be changed to show the popup only if you actually can accept that answer.