Found by testing for #1658 with:
With python2, the rendering is broken, with python3 the client crashes!
r19645 adds better debug logging.
The problem seems to come from relative vs absolute coordinates: some methods call
queue_draw with relative coordinates, others expect it to honour absolute coordinates and repaint the whole window, including the padding area..
Large fix in r19647, also fixes the crashes with python3. (looks like cairo / python3 doesn't do enough validation and just crashes... python2 just renders junk?)
queue_draw is part of the GTK API, we should always use absolute window coordinates there.
Other related changesets:
this ticket has been moved to: https://github.com/Xpra-org/xpra/issues/1874