From Olivier: - When an histogram with negative content only was painted as a filled   area, the drawing exited the pad.
From Olivier:
- When an histogram with negative content only was painted as a filled
  area, the drawing exited the pad.


git-svn-id: ecbadac9c76e8cf640a0bca86f6bd796c98521e3@11111 27541ba8-7e3a-0410-8455-c3a389f83636

dawehner/root,dawehner/root,dawehner/root,dawehner/root,dawehner/root,dawehner/root,bbannier/ROOT,dawehner/root,bbannier/ROOT,bbannier/ROOT,bbannier/ROOT,bbannier/ROOT,bbannier/ROOT,dawehner/root,bbannier/ROOT