In Mac OS X Lion, applications can make use of a feature to auto-save and version files. This feature locks files that are inactive for editing and when the file is unlocked then starts automatically saving versions. If you have a problem with the file you can then always step back to a previous version of the file. The feature is manifested in the title bar and the file menu of applications that make use of it. When you open a file, it can be locked. Viewing the file in the Finder also shows that it is locked. Clicking on locked provides the option to unlock. Once unlocked you can…