title: Qt 5 under Ubuntu (GTK) - no default 'Open File' Dialog
body: <p>I've been using Qt5 installation from <code>apt-get</code> under Ubuntu 14.04 LTS.</p>
  
  <p>Now I uninstalled that, and installed from the Qt website. The problem is that now the 'Open File' dialog is not the GTK's default anymore, but the Qt's minimalistic version (see Picture below):</p>
  
  <p><a href="https://i.stack.imgur.com/3fOUp.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/3fOUp.png" alt="enter image description here"></a></p>
  
  <p>How do I reactivate GTK's default 'Open File' dialog, as in the picture below?</p>
  
  <p><a href="https://i.stack.imgur.com/b3Muh.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/b3Muh.png" alt="enter image description here"></a></p>