Undo doesn't work as expected

If you draw on one object, then select a different one and press undo many times, nothing happens, but when reselecting the first object and pressing undo once, it undoes the same number of steps back as the number of times you used undo with the other object selected. This can cause problems if you select the wrong object by mistake, attempt to undo, realize you have the wrong one, and try the right one, only for it to go many more steps back than you wanted. As there does not seem to be a redo function, this can result in a good deal of work lost.