Dear Allin and Jack,
this is just a suggestion which may raise gretl's already high-level usability even further a bit.
Personally, I like a dark background and bright letters very much as it nicely suits my eyes. Of course one could use any editor which supports differently coloured backgrounds but then one has to abstain from some other features the default GUI script window offers, as you know.
I've no idea how difficult it is to implement and if this would be helpful for others as well. Don't take this as urgent!
Best wishes,
Artur