Thanks for doing that.
I see it just lets you create the shapes by clicking on the backgroud. For a rather harsh use of the word 'just'. That is better than anyone else has managed
However, what we really want is the ability to edit the shape once you have drawn it, by dragging a corner (or other appropriate part of the shape).
I am inclined to leave this un-merged for now, but it is useful to have your code as starting point.