[Ohrrpgce] SVN: teeemcee/8036 mac/gfx_sdl: work around SDL bug: SDL_WarpMouse failed to hide the mouse

[subversion at HamsterRepublic.com]

teeemcee
2016-06-05 05:28:23 -0700 (Sun, 05 Jun 2016)
450
mac/gfx_sdl: work around SDL bug: SDL_WarpMouse failed to hide the mouse cursor

This only occurred when the mouse cursor was off the window and got
warped onto the window by a call to gfx_setmouse while the mouse
cursor is meant to be hidden, such as in the tile picker when arrow
keys are pressed.

There is definitely an SDL bug here, because I had to call SDL_ShowCursor twice
to work around it, indicating SDL has lost track of the cursor state.
---
U   wip/gfx_sdl.bas