[Ohrrpgce] SVN: teeemcee/12459 gfx_sdl2: rewrite "mouse region"/io_mouserect handling so the mouse move

[subversion at HamsterRepublic.com]

teeemcee
2021-09-23 05:42:33 -0700 (Thu, 23 Sep 2021)
338
gfx_sdl2: rewrite "mouse region"/io_mouserect handling so the mouse moves/accelerates normally

Previously it used SDL's relative mouse mode, which turns out to display mouse
acceleration. Plus there were mouse movement glitches when entering/exiting
mouse clipping. Also, it forced hid the OS mouse cursor, unlike all other gfx
backends.
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U   wip/gfx_sdl2.bas
U   wip/whatsnew.txt