I have had a surprisingly high number of clear nights recently and SGP has worked its magic all night long. I thought I would grade my images so far and weed out the poor ones, ready for the final session.
In the grader tool, I accidentally marked them all as BAD, causing their filenames to be prefixed by BAD_.
Without an obvious UNDO instruction, I selected them all again and marked them as GOOD.
To my dismay, all my frames were prefixed GOOD_BAD_…
Just as well I could remember the old DOS 5.1 REN command to rename them all - but it would be better if there was an UNDO command that could sort it out!!