Yeah I was using AGI studio, an old version (1.2.4) that could run in Linux. It took a little while to get the hang of editing the history without accidentally wiping everything out, or nuking an important drawing step that took a few minutes to do. And figuring out that if you do a fill and it escapes and ends up filling half the screen, then you actually need to go through all the steps and probably fix up one of the really early steps, you can't just delete the last step. I'm guessing there's an optimisation to remove duplicate drawing instructions, so if you've got lots of drawing steps it can take a fair bit of hunting. And there's no undo, and to me the way steps are deleted was counter-intuitive, so I kept accidentally making 'off by one' errors with step deleting :) Like if you had step 3 selected, and clicked delete, then it would actually delete step 4 (or something like that).
Once you get the hang of it, it's ok.