Here are some things that are not working for me, probably because they are not implemented
* TEK_COLOR (pro file is available by IDL and is very simple, so I don't know which would be the more elegant solution for inclusion in GDL)
* "SHADES parameter in SURFACE not allowed"
* "SAVE parameter not supported in SURFACE"
Which is the state of this things and what can I do for helping?
There is information on this page about making contributions: http://gnudatalanguage.sourceforge.net/support.php
My understanding is if you implement something that want working you can submit it via the tracker.