You can use the GFF Editor from Bioware, but this version
Modfied GFF Editor
from Roboius was "fixed" so it won't filter out files that are (internally) really GFF files from the Open File dialog.
It has an ASCII export function.
If you use the latest version of my Kotor Tool with the GFF Editor in the same folder, it will launch it when you double-click on a file that is in the GFF format.
You can download it at:
The next version will include some other files types that I did not recognize as GFF-based when the above release was coded.