Hi!
Somehow, the sidebar does not work well when working with multiple screen, since it is only attached to the sides of your main screen. When the sidebar should be "hidden", it appears in fact on the second screen and starts moving right-and-left as soon as you moved a bit over the srceen border.
You might say: Well, then place it just on the other border of your main screen. This only works as long as you're satisfied with two screens...
I hope this bug gets fixed soon.
Pascal