You should add keyboard hotkeys to change between the newly added rows of skill belt selections; I recommend defaulting to Page Up to go up and Page Down to go down (or better yet Shift+W to go up and Shift+S to go down, or maybe Q and E, or Shift+Scroll Wheel) It would also be nice if the GUI buttons to scroll through the rows were a little bit larger when you have the skill belt enlarged (as it is it actually seems like enlarging the skill belt makes them smaller; although I'm pretty sure that this is just an optical illusion)
Yeah, this would be a good call. Dunno what, though. And the scroll wheel would be a good candidate if it wasn't crashing the game right now.
Go with Shift+W and Shift+S then. On further thought these would probably be the most convenient of all my suggested schemes. (In fact, even if you get the mouse wheel working you should go with a keyboard shortcut as well. It's more important to have a keyboard shortcut for this than a mouse shortcut since it already has a GUI element; it would be better to add keyboard-only functionality where there is none than to improve mouse-only functionality where we already have mouse-only functionality)