title: Bind File -> Open File with GUI dialog to C-o as global-set-key
body: <p>I want to bind GUI dialog <code>File -&gt; Open File</code> to <code>Ctrl</code> + <code>o</code></p>
  
  <p>I can <code>(global-set-key (kbd "C-o") 'find-file)</code> but I want it exactly with gui.</p>
  
  <p>How can I do it?</p>