title: Simple Opera plugin
body: <p>How to write a simple Opera plugin?</p>
  
  <p>I'd like to develop a plugin that would change the <code>Referer</code> header of a request based on request's url data.</p>
  
  <p>Opera's website says plugins should be developed using <a href="http://en.wikipedia.org/wiki/NPAPI" rel="nofollow noreferrer">Netscape4 Plug-in API</a>. However there's not so much information about it available. I looked up in my <code>c:/program files/opera/program/plugins</code> and it seems like Opera's plugins are <code>.dll</code>s. What programming language should be used for Opera Plugin Development and do you know of any walk-through about it? </p>