Happens a lot, especially when multi-tabling. Or when I was watching a replay of another hand and I'm clicking, say, "Play" and suddenly the background game comes forward and I click Call. Did 2 things to fix this small issue:
1. I now use the Layout option whenever I'm multi-tabling so I can view all the tables in my screen and each of them only takes up one small portion.
2. My poker game
doesn't suddenly show up out of nowhere on my computer screen, because I disabled the "window priority" on the room settings. Now whenever it's my time to play, the software tab starts flashing orange and I only open it when I want to. Not only does this avoid misclicks, now I can be watching a video or reading a book or browsing online for anything and it doesn't mess it up.
Now, if you're talking about misclicking in a normal game situation, when everything is going normally and you just so happen to click the wrong button, then no, doesn't happen to me :P
Good luck at the tables!!