One observation: Mellel (see www.redlers.com ; the keyboard shortcut from within Mellel is command-option-s) can do the same thing, but also has tons of other features as well.
Considering how much love WriteRoom gets for full-screen editing, I'm surprised Redlers doesn't crow more about this feature.
Considering how much love WriteRoom gets for full-screen editing, I'm surprised Redlers doesn't crow more about this feature.