Requires N:M mapping
This mapping has 1 all-to-all group: every node on one side corresponds to every node on the other, and none is deleted or inserted. Each member carries an all N:M badge; selecting one highlights all of its counterparts, in the tree and in the code view alike.
A painting is a person's account of this edit as text, recorded independently of the node mapping - a rendering often has several equally defensible answers where the mapping has one. Deletions and insertions carry no position on the opposite side in a painting, so that panel draws no caret for them.