title: How to draw a custom shadow in GTK?
body: <p>I've created a custom window in GTK3 and set <code>decorated</code> to <code>False</code>, so the default window decoration is not rendered. That also removed a shadow from my window.</p>
  
  <p><strong>How do I get the shadow back?</strong></p>
  
  <p>Should I use Cairo library to draw it? If so, any tips on how to do that would be helpful.</p>
  
  <p>I'm writing in Python, but examples in any language will work.</p>