You'll have to bear with me, I don't know much about how Java actually works but I really appreciate your help. Before I try to apply anything can you explain exactly what I should try to do with that mouse fix you linked?
I've tried to add that JVM argument before but I can't maximize the window, or enlarge it at all, after it's applied. I've tried "windows key + up" and "alt + up". If I maximize the window manually, there still always remains a white bar at the bottom of the screen.