Vim Recipes ‣ GUI (GVim) ‣ Maximising Screen Space
The toolbar, menubar, and other GUI artifacts take up too much of your screen; you want to hide them.
Modify the guioptions variable. Gvim decides which elements of the GUI to display based on the value of guioptions. This is a series of letters, each of which refer to some specfic element. Some examples follow:
So, to hide the menu bar, toolbar, and scrollbars you could use :set guioptions-=mTrlb. To display a hidden element use += instead, e.g. :set guioptions+=T.
If you decide that you want to restore one or more of these elements you can simply execute :set guioptions+=m, for example. This can be cumbersome, however, as it requires you to remember the significance of each letter.
The following stanza in your gvimrc assigns <F11> to toggle the display of extraneous GUI elements:
function ToggleGUICruft()
if &go==''
exec('se go=mTrL')
else
exec('se go=')
endif
endfunction
map <F11> <Esc>:call ToggleGUICruft()<cr>