title: vimrc different colorscheme when file is read-only
body: <p>I have this in my .vimrc file to show a different colorscheme in gvim.</p>
  
  <pre><code>" Colorscheme, options for GUI only.
  if has("gui_running")
      colorscheme clean
      set guioptions-=T
      set guitablabel=%t
      set background=dark
  endif
  </code></pre>
  
  <p>What syntax can I use to only show a particular colorscheme depending on whether a file is readonly?</p>
  
  <p>(Thanks to <a href="https://github.com/matason/vimstuff/blob/master/.vimrc" rel="nofollow">https://github.com/matason/vimstuff/blob/master/.vimrc</a> for a great .vimrc example).</p>