Document Versions on Mac OS X 10.7 Lion

Problem: When you start TrailRunner on Mac OS X 10.7 Lion, it may happen that the system is asking you if you would like to Duplicate the current document or Unlock it.

Background: This is a new system wide behavior in Mac OS X 10.7 Lion to prevent users from accidentally overwriting a documents content if not used for a longer time. In TrailRunner however it does not (always) make sense, because you generally work with only one document, which is TrailRunner.trail, stored in your Application Support folder. But the new versioning mechanism itself does makes sense, as it is a fast backup restoration method while working in your network of tracks and accidentally breaking up things.
Solution: Whenever this dialog comes up, klick on the Unlock button, because that is what you would expect.

Expert Note: The three choices have the following meaning: Unlock lets you edit the file as you would have in earlier versions of Mac OS X (and it keeps versions behind the scenes), Cancel is your panic button, and Duplicate creates a new file you can start with. In the end it doesn't really matter which option you choose. TrailRunner will always re-open the last saved document on the next application start, which is either the unlocked original or the duplicated new document branch. To be sure where the system has actually stored your unlocked or duplicated document, you can check the place by command-clicking the document title and inspect the location.

Sidenote: Interestingly even Apple itself has some problems with the new system feature.