NewGUI: mouse wheel support
|Reported by:||eriktorbjorn||Owned by:||fingolfin|
This is an attempt to add mouse wheel support to the NewGUI list and scrollbar widgets. (I haven't looked much at the NewGUI code before. I hope I didn't mess it up too badly. :-)
Of course, this means the backend has to be updated slightly so that it will generate EVENT_WHEELUP and EVENT_WHEELDOWN events. I only know enough to do this for the SDL backend, and only for SDL 1.2.5 and later since it uses the SDL_BUTTON_WHEELUP and SDL_BUTTON_WHEELDOWN constants.
It's probably easy to support earlier SDL versions, but I didn't see much point in doing so.
Ticket imported from: #620627. Ticket imported from: patches/190.