Quite a few of us old timers have been bitching about the fact that Apple got rid of "Save As..." in the document model.
But few have noticed that it actually creates a situation where you LOSE DATA! This should be filed as a Priority 1 showstopper bug. Anything that causes you to LOSE DATA is a bad thing. In fact, the main argument Apple made in favor of persistent storage instead of having Save and Save As was so you wouldn't lose data.
First, the dialog box from Hell:
I was editing an important file, but left it open (commonplace, and usually not destructive). Meanwhile, I edited the same file on another computer, with different changes, and saved it to my shared (Dropbox) location, so it sync'ed out from under TextEdit.
This has happened countless times in the past, and TextEdit was smart enough to notice it, and tell me not to save over the other file. This dialog box purports to do the same thing, BUT WITH A CRITICAL DIFFERENCE. It does not allow me to Save As... to preserve my changes (because Save As... is not a feature any more!).
My two choices are [LOSE CHANGES] and [LOSE OTHER CHANGES]. How is that a good choice?
I had to think about this one for a while, and I went out to the Finder, made a backup of my file, clicked "Save Anyway", then manually merged the changes between the two files. Messy, and not for the faint of heart.