[matplotlib-devel] switching to PS/SVG backends

I've noticed a problem as follows:

You run a GUI backend (GTK, GTKAgg etc) and want to save a figure.
You select the toolbar save button and type in a .ps or .svg filename
and select save.
The GUI backend switches to the PS/SVG backend to save the file.
If there is a problem saving the file, for example you do not have write
permission to the directory, PS/SVG backends will kill your GUI
application with sys.exit()

I don't think failure to save a file should be a fatal error.
Perhaps PS/SVG print_figure() could raise an exception for the GUI
backend to catch so it can popup an error message and continue.

Steve