A shape tool now takes a press as a bounding-box handle's only on the
drawn handle square, kept square to the screen: 3 screen points from the
handle's centre along each axis at the default Anchor Size, a half point
more or less per step. A press just beside a handle draws a new shape.
drawing_gestures_snap_to_smart_guides started its second rectangle on the
first rectangle's corner handle, which stays selected; it now deselects
first.