title: Make custom file open by a custom program VB
body: <p>How to make a file (<code>.jkl</code> extension for example) that when you open it, your custom program will pop-up.</p>
  
  <p>For example:<br>
  I have a <code>test.jkl</code> file<br>
  If i double-click it, my program will be the one to read it.<br>
  Just like a .jpg file extension, when double-clicking the file, paint will pop-up and shows the image.</p>
  
  <p>My code when changing the file ext is just simple</p>
  
  <pre><code>File.Copy(origFile, origFile.Replace("txt", "jkl")
  File.Delete(origFile)
  </code></pre>
  
  <p>So now i have a <code>.jkl</code> file, now what I need to do is when the user double clicks the <code>.jkl</code> file, this program will automatically open, ask where to save it, and change it back to <code>.txt</code> to the path where the user wants to.</p>
  
  <p>How can I do this?</p>