Either add controls for what actions you can undo, or make it more user friendly! e.g While i am animating i sometimes move an element in the timeline. hitting undo will not change this it will change something else, i then have to change the timeline as well as whatever else was undone.
if no changes have been made the program should not prompt for a save it can be confusing, automatic saving should be an option as well, with flexibility for prompting me to save or saving automatically. Work does get lost.