Problem:
X window drawn by the gtk3agg backend (in interactive mode) remain partly
obscured if another X window is moved to partly obscure, then moved away.
Doesn't happen with X windows generated by other X applications or host's
(where xserver running) native windows (ie only matplotlib figures
I have a matplotlib application which can display a plot or write it
to a file based on command line flags. I have discovered that if it is
run without DISPLAY set (say, from a crontab file) that the default
backend (I have no matplotlibrc file) attempts to chat with X, causing
crashes. I've worked
