In vim, if code conventions clash, you may need a quick way to switch the indent width. Here is how you can map your function keys to an indent of 3 or 4 spaces.
Simply add a few lines to your .vimrc file:
"basic settings "replace tabs with spaces set expandtab set shiftwidth=4 set tabstop=4 set softtabstop=0 "map F3 to 3/4 spaces when in normal nnoremap <F3> :set expandtab tabstop=3 shiftwidth=3 softtabstop=0<CR> nnoremap <F4> :set expandtab tabstop=4 shiftwidth=4 softtabstop=0<CR>