Bug fix #33892

HiDPI "retina" mode didn't work for "Continuous Grab" yet.

Note; this mode works by having different coordinate systems
for pixels and window/mouse coords. I really hope future
HiDPI implementations use the same trick.



git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@53878 954f8c5b-7b00-dc11-b283-0030488c597c