title: Set custom protocol handler in Firefox?
body: <p>I'd like Firefox (running on Linux) to open a custom protocol with an external application.</p>
  
  <p>For example urls starting with <code>gvim://</code> protocol name should launch gvim and pass the rest of url.</p>
  
  <p>I tried to set <code>network.protocol-handler.external.gvim</code>, <code>network.protocol-handler.app.gvim</code> by <a href="http://kb.mozillazine.org/Register_protocol#Firefox_3.5_and_above" rel="noreferrer">Mozilla's knowledgebase</a> however Firefox still throws <em>unkown protocol</em> error message when attempting to open <code>gvim://</code> url. But no prompt on how to handle this protocol was offered. It seems the knowledgebase is outdated for Firefox ver. 27.</p>
  
  <p>Any ideas on how to properly configure custom protocol handler in recent Firefox versions? I am running Linux without GNOME.</p>