I have an external monitor plugged in to my MacBook. It's positioned above my mac, so I arrange the screens accordingly in the display preferences pane. However, I can't drag any windows from my macbook's display to the external as they get "blocked" by the menu bar. If I move the menu bar from the macbook display to the external display (is this a new feature in mountain lion?), everything works as it should, but I don't want to have the menu bar and dock on the external screen. Is there anyway around this? For now I've just changed the arrangement in preferences as if they were side by side, but this isn't ideal... I had this same setup on Lion and didn't have this issue. Not sure if it's a bug or just a side effect of the movable menu bar feature.