I like using Scrivener’s fullscreen mode for writing. No fuss, no menus, just the text and nothing else.
I also like its completion mode: “Edit > Complete”. However, the default shortcut for this uses the Escape key, which exits fullscreen mode. What to do?
Well, on the Mac at least, you can add a new shortcut via the “Keyboard” section of System Preferences. I bound Control-Space to Complete, and now I can complete words without exiting fullscreen mode.
As an added advantage, this keyboard shortcut is the same as other coding applications I use, so it’s more familiar.