MacVim fullscreen mode

To enter fullscreen mode:

:set fu

To leave fullscreen mode:

:set nofu

For more info on fullscreen mode:

:h 'fullscreen'

Grow to maximum horizontal size on entering fullscreen mode:

:set fuopt+=maxhorz

For an example config, check out my .gvimrc file here, specifically:

set fuopt+=maxhorz                      " grow to maximum horizontal width on entering fullscreen mode
macmenu &Edit.Find.Find\.\.\. key=<nop> " free up Command-F
map <D-f> :set invfu<CR>                " toggle fullscreen mode