Pressing "Undo" followed by "Clear Errors" will penalize you

[uigrad]

I've been trying to figure out how I've been penalized for incorrect marks sometimes after I hit "Clear Errors", even though nothing is changed in my grid.

It seems that pressing Undo changes what you see, but doesn't change what is cached. When you choose to "clear errors", it looks at the grid after you made your last mark on it. If that grid has any errors, you are penalized (even if you tried removing those marks by using Undo).

To reproduce:

Make one or more correct marks.

Make one or more incorrect marks.

Press undo enough times to remove the incorrect marks, but leave some correct marks.

Press "Clear errors". No errors will be cleared, but you will be given a penalty.

[pub4]

if i think about it, i'll place another mark before pressing 'clear errors.' sometimes i forget, and of those times, sometimes i'll get a heavy penalty.