Bug fix:

On screen/area refresh calls the header scroll offset was cleared too. 
Probably an old remainder of early 2.5 coding. Should be not needed so much.



git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@55572 954f8c5b-7b00-dc11-b283-0030488c597c