[Trunk[ R4786 Undo
Most of the time Undo works very well, but I found that most of the items on the Lines palette do not play well with Undo. If you place hairpins or anything from 8va down, select and delete, then undo several times to get the score back to a clean unmodified state, the placed elements come back and stay. A save and load of this score shows they are still there, they are not artifacts or remnants. However, the voltas and slur elements don't seem to do this.