Could someone please remind me of how you make multiple saves for the level you're working on? So you can back up to an older save if, or rather when, something goes wrong.
I just lost all the objects on a level last night, I still havn't figured out what happened but I can't back track now

Could it have something to do with the annoying warning about an object being locked by source control (or something) that pops up when you tries to delete an unwanted object and then just moves it to the corner of the map?