I loved the F9 fold/unfold in AMos Basic. BB3d/IDEal also had fold/unfold and it never crash (for me!)
me too(amos pro)!
What I have coded so far in glbasic had no problem folding/unfolding.
You have to have comments inside. I have not tested if the //coments on a single line had error, or just if you added the //comment after a sentence (as I do)