SDL_GetMouseState
once per tick to update the mouse position. The upcoming SDL 2.0.4 will have updated mouse functionality which Gosu will probably make use of, plus lots of bug fixes. So one quick fix you might try is to use the latest version of SDL 2 from Mercurial (which should be pretty close to the final 2.0.4 version by now).
Powered by mwForum 2.29.7 © 1999-2015 Markus Wichitill