Box Drawing Strategy does not draw the bottom line of the box always correctly

The Annotation Editor can visualize annotations with a Box drawing style. If a new annotation which
is drawn with this style is added, the bottom line of the annotation is missing.

The reasons for the missing bottom line is, that the drawRectangle call draws the box outside of
the clearing area. To solve this issue just reduce the height of the drawn box by one.
Another solution would be to increase the clearing area.