when I alt-tab and then get back to WoW the bars are frozen like I am still pressing ALT. I have to press ALT again to put the actionbar in the default view

I cannot prevent this behavior, as there is no available API to check if WoW is running in the background or has been reopened.

maybe for the alt-tab issue could you do that when I press a modifier you start a timeout that checks if modifier is pressed every tot ms? this way when I get back in wow the timeout checks out I'm not pressing anymore and then should update the bars accordingly