Undo trolls drawings problem

I detected an issue with the feature to delete all the drawings of a troll after kicking him. It happened to me two times that, after kicking a troll that was ruining my drawing, some of the traces remains. Most of them are cleared, but for any reason, some times some traces remains. Both times it happened to me, I kicked the troll in less than 10 seconds since they started ruining the drawing.