intelligent transform handlers positioning

The problem:
create a large object (about 600% of the view).
when working with it you cannot scale the object - UNLESS you are lucky and you are looking at the exact center of an edge.
So most of the time you have to scroll/pan around to find the scale/skew handlers when looking at large objects.

The idea:
position the size/skew handlers on the edge of the boundingbox, but on the _visible_ center of the edge, not the absolute center of the object.
that way you can always scale without searching the handler.

note:
this obviously won't work with the handlers on the corners.