Can I put the pen on top of a sprite?

[cymplecy]

A recent thread

Make pen marks appear on top of sprite

I don't use the pen much but want to be able to write on top of another sprite when I click on it but not managing to do this What am I missing (or will I have to make the white parts of my sprite costume be invisible)? https://snap.berkeley.edu/snap/snap.html#present:Username=cymplecy&ProjectName=Futoshiki&editMode&noRun