demo of box move- click/drag with gang box button

demo of repositioning boxes. Click and drag using gang box button. The
code isn't pretty, but maybe we'll be able to change this, especially
if want to do this on a wider scale, for all motor boxes and sensor
boxes.

See new lines 712-747, referring previously to lines 750-762, and
507-518, 460-462 as well
Merge branch 'John'