Bug fix: scrolling workspace break show/hide animation #109

Due to the workspace switcher having been set not reactive
(880e8941f0daede4e251c1449a0863371387918a), hover status is set to true even if
the mouse has left the dash triggering the hide animation. The animation was
then stopped by checking fot the hover status, but no new animation was
started. The bug is due to old code: previously the workspace switcher was
alwasys making the hover status false, and the bug didn't appear.