It always astonishes me that undo, redo, and auto-save are implemented without relying on a logging mechanism akin to databases' "write-ahead logs". To me the

It always astonishes me that undo, redo, and auto-save are implemented without relying on a logging mechanism akin to databases' "write-ahead logs". To me the main problem of maintaining "redo" actions is of identifying them. They are unnamed, and presenting and recognizing an alteration is hard.