The Dimension shape could really use some tweaking. First and foremost, the user should be able to have the dimension indicate the exact length by having a field to type the numbers into rather than trying to manually size it with the mouse while it's being created or edited. Second, the thickness of the line needs to be editable. For these first two, the start and end coordinates and the line width that can be typed in for the line shape would be acceptable for the dimension shape. Third, the type of arrowhead should be editable to include a sizable arrowhead, a short diagonal line, or a filled circle. And finally, the font type and size need to be specifiable. The current size slider doesn’t work right when you move it toward the largest extreme. The dimension becomes three dots.