title: how to make a opened buffer read only without reloading again with 'find-file-read-only'
body: <p>I like to have my coding buffers read-only when I am not editing them (like Vi modes edit, read-only). For that, I can use <code>C-x C-q</code> for turning a emacs buffer on/off the writable status. Seems that this write-locking feature has some inheritance from RCS or similar way of file-loking/revision-system so working with files under Version Control does not work:</p>
  
  <pre><code>C-x C-q
  File is under version-control; use C-x v v to check in/out 
  </code></pre>
  
  <p>I don't want to check in/out I want only to prevent "cat-typing". I can write a macro flip-flop find-file-read-only '/'find-file ' and give some key-binding to it but I am sure there would be a solution inside emacs or .el written already. Any suggestion?</p>