In my attempt to use the SolarSoft (http://www.lmsal.com/solarsoft/) with GDL I encountered the message:
% Keyword parameter SET_FONT not allowed in call to: DEVICE
Maybe this isn't a severe problem but could be nice to have.
This keyword is now ignored in the CVS version so it does not stop execution:
GDL> device, set_font='s'
% Warning: Keyword parameter SET_FONT not supported in call to: DEVICE. Ignored.