Press F4 to toggle the diff of currently open
" Press F4 to toggle the diff of currently open buffers/splits.
noremap <F4> :call DiffMe()<CR>
let $diff_me=0
function! DiffMe()
windo diffthis
if $diff_me>0
let $diff_me=0
else
windo diffoff
let $diff_me=1
endif
endfunction