I recently discovered Gpredict and have found it to be a very useful program to supplement traditional teaching materials in satellite geodesy courses. Many thanks to Alexandru Csete for making the program and code available! I would like to make a few suggestions for minor revisions:
Allow the footprint demarcation line to be turned off (not just the footprint highlighting).
Cause the program to remember the settings of both the footprint and ground track visibility settings. I am constantly having to go back to the right-click menu to turn ground track back on.
Add a setting for the line thickness of ground tracks and footprints, even if just thin and bold options. The current line thickness can seem a bit too thin sometimes.