I really love this app. Its making what I thought was going to be a tedious write up into a pleasure.
I am writing a document, whilst referring to another alongside in a split pane, therefore not using full screen mode.
Is it possible to get the cursor to center vertically on the page like it does in full screen?
Exactly as Juddbert says. Typewriter mode is on by default for full screen mode, but off by default for the regular editors. But you can turn it on or off for either as you wish (Text > Typewriter Mode).
(This assumes you are using the latest version, 1.10 - prior to that this was set via the Preferences.)