Bug or not. Preference to not append file extension in CS4 vrs CS5. In CS4 if you turned the append extension to never, it it wouldn't append the extension for the file type in the save as dialog. If you typed in one yourself it would ignore what you type cause it just didn't care. ie. i have a file and i name it file.eps it would save the file as file.eps. I had to manually type the extension, something i prefer and the reason why i had the never save file extensions chosen in the preferences. In CS5 with the same preference set up if you type file.eps it removes the .eps from the save as dialog. The first time this happened i went hmmm retyped it and hit save. It saved the file with out the extension and overwrote my working layered file with a flattened eps file with NO prompting or warning. This is very concerning to me.