Snap! has the ever-useful "pen trails" block, but I have no idea how to reset the pen trails of just a single sprite! :')
The "pen trails" is global, with all the the paintings (from moving sprites with the pen down) and printings (from the "stamp" block) of all the sprites (also deleted sprites, clones...).
So you can't reset a "sprite pen trails".
But you can store partial "pen trails" before "new paintings" and then, if the new result is not fine, you can restore the previous state.
Something like this...
Joan
The "pen trails" is global, with all the the paintings (from moving sprites with the pen down) and printings (from the "stamp" block) of all the sprites (also deleted sprites, clones...).
Ah! I see! Somehow I'd thought otherwise. That makes sense. And huh! - that's a pretty clever solution, thanks. :')