I believe that, if nothing else, this must be fixed in the poker game programming. From what I can tell so far, the first to act after the flop does not need to be the button holder. I think that it might be the case that the last to act after a flop switches To the big blind if the small blind folds....? This makes the person after the big blind first to act after the flop sometimes. SOMETHING is making this happen, and I REALLY hope they can fix it... This absolutely destroys some aspects of poker logic and is flat out unfair to those who know a little about the importance of position at a poker table!
Now, people joining or leaving the table often effects the position of the button, which I think might be the same in real life (Though. I believe the metrics might still be off in torn). But when people time out and rejoin, or leave and are replaced, I have seen the button do a few crazy things. I have seen someone with the button switch seats between hands, and the button followed him to the other end of the table!