Not sure if this is a bug or request. But when additional genres are added you get the scrollbar which is all good. But when you move the bar that splits the "movie search" and "movie info" the genre filter does not increase in size. It stays the same size with the scroll bar. It would be good if the box that contains the genre filter increased in size just like the movie list and search boxes do.
Sorry if this is more of a request then a bug. because i'm sure it's currently doing exactly waht you programed it to do.