Well, instead of "whole polygon" I should say "all the visualizations
associated with a scalar". In edit mode you'll get a bounding box around the scalar and
you can drag it just as any pd object. The [struct] outlet will notify you with a
"displace" msg when you do this, and you can use the pointer element from that message to get
the current x and y for that scalar.
I thought that with "whole polygon" you meant the big canvas in the
background. that's the problem I was pointing at, how to make it possible
so that a click in the background (without the mouse detector) can make a
scalar move instantly there.