* Less flickering when drawing the label: the area of the label is now
clipped, so there is no need to fill the background again.
* Consumed the last reserved member for the bounding box of the label.
* More or less rewrote the header.
git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@15747 a95241bf-73f2-0310-859d-f6bbb57e9c96