I use F3, F4 and F6 quite a bit. Every once in a while, by accident, I hit F5 and get a dropdown list of random words (not most recently used even) -- unless I'm careful and do Command-Z, the dropdown text becomes a part of the text. I have TeXShop Preferences>Editor>BibDesk Completions turned OFF. Is there a Mac OS system thing going on here? Thanks. SGM