This happens predominantly with timelines though can happen with sound files also when I have been creating presets, either way it is frustrating as many hours of painstaking work is lost. If I create a timeline or modify one and do "close" or "quit" from the menu I expect to be prompted (like any other application) if I want to save my changes, sometimes this does not happen and ahving not saved the changes explicitly they are lost. Is this a known bug ? Is there anything I can do - apart from being more vigilant and saving my changes manually - to get prompted if I want to save the file ?