Original bug: https://projects.blender.org/tracker/?group_id=9&atid=127&func=detail&aid=3760 Code remove in revision 6654: http://projects.blender.org/plugins/scmsvn/viewcvs.php/trunk/blender/source/blender/src/renderwin.c?root=bf-blender&r1=6491&r2=6654 and return in revision 6839 (without the point checking): http://projects.blender.org/plugins/scmsvn/viewcvs.php/trunk/blender/source/blender/src/renderwin.c?root=bf-blender&r1=6835&r2=6839