title: How to associate application with existing file types using WiX installer?
body: <p>Related to this: <a href="https://stackoverflow.com/questions/138550/how-to-register-file-types-extensions-with-a-wix-installer">How to register file types/extensions with a WiX installer?</a> but not a duplicate.</p>
  
  <p>I need to handle existing file types (.jpg files).</p>
  
  <p>I do not want my app to be the default handler for .jpg. I would just like to extend the "Open with" menu with a link to my app.</p>
  
  <p>I see <code>HKCR\.jpg\OpenWithList\</code> and <code>HKCR\.jpg\OpenWithProgIds\</code> in the registry but I am not sure whether to write to these and how to do it correctly with WiX. Should I use something like this?</p>
  
  <pre><code>&lt;ProgId Id='??what here?' Description='Jpeg handled by my App'&gt;
    &lt;Extension Id='jpg' ContentType='image/jpeg'&gt;
      &lt;Verb Id='openwithmyapp' Sequence='10' Command='OpenWithMyApp' Target='[!FileId]' Argument='"%1"' /&gt;
    &lt;/Extension&gt;
  &lt;/ProgId&gt;
  </code></pre>
  
  <p>There are many ways to fail here (like Photo Mechanics did, the HKCR for image file types is a real mess after I have installed this software).</p>
  
  <p>How to do this correctly with WiX?</p>