title: how to get a active gtk window in gtk3?
body: <p>I have tried like:</p>
  
  <pre><code>gdk_screen_get_active_window(gdk_screen_get_default());
  </code></pre>
  
  <p>But it return gdk window, and that's not what I want .</p>
  
  <hr>
  
  <p>The reason for need gtk is that I want to get the active window's location by:</p>
  
  <pre><code>gtk_widget_get_allocation
  </code></pre>
  
  <p>anyone know how to do this?</p>