Not really a problem, as I can get out of it, but a nuisance all the same.
Every now and again, I will select something on a drawing, or draw a line, circle or whatever, and the whole drawing goes RED! Have no idea why, if anyone can shed some light on this I would be grateful.
Am using V.11 on Mojave, but it happened on V.7 on Sierra too before.
I get out of it by clicking somewhere on the drawing, or selecting another drawing tool and start another whatever that tool does, or some similar such action. Just damn annoying!