Bugfix #34365

Tiny tweak.

Dragging option (cursor change) for region dividers in editors was having an 
un-even sensitivity hotspot. This conflicted with header buttons for example,
where the hotspot and bottons overlapped.

Now the hotspot is around the region-edge evenly.




git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@55163 954f8c5b-7b00-dc11-b283-0030488c597c