Greg reported me bug about Graphos and I think it is a GS bug, since
it works on Mac.
During printing, objects should not drawn their editors (= shape or
path handles). To do that, I use:
if ([[NSGraphicsContext currentContext] isDrawingToScreen])
[editor draw];
thus I suppose that on GS (cairo backend at least) it returns true
even while printing.
Testing is simple: Launch graphos, select some shape, look at the
handles, print (preview). The handles should not print. They do on GS,
they don't on mac.