I would like to suggest that Rapid PHP (or I suppose all of the Rapid line) support auto-save. This feature would be different than the auto-backup that's currently implemented and is done very well in JEdit (one of the few things I miss). Here's how it works:
Every X minutes (default 1 to 3) all the open documents that have been changed since the last save are saved to ~filename.php (you can of course use any naming scheme) and the workspace environment (which files are open) is saved to Rapid PHP's settings. None of this action marks the document as saved - Rapid PHP and the user still see an unsaved document, and the user still gets prompts when exiting - but the backup is there in case something happens.
If your power goes out (or the system, or Rapid PHP, crashes) the next time it starts up it restores all the files from the saved workspace. When doing so it sees the auto-saved files and loads them instead of the main files (you would probably want to build in a file modified check in case the main doc is somehow newer). Once loaded then auto-saved files are still marked as unsaved since the user hasn't specified to overwrite the main files yet.
One of the great things is you can also support unnamed files. ie: you create a new file and start work on it, but the power goes out before you get a chance to save, Rapid PHP has already saved a ~unnamed.php document with your work in it and will restore it automatically as an unnamed document when you start up.
What this comes down to is a persistant, crash proof workspace that's completely transparent to the user. A big selling point for Blumentals, and a big bonus to users like me
