title: Qt: How to force a hidden widget to calculate its layout?
body: <p>What I am trying to do is render a qwidget onto a different window (manually using a QPainter)</p>
  
  <p>I have a QWidget (w) with a layout and a bunch of child controls.  w is hidden.  Until w is shown, there is no layout calculations happening, which is expected.</p>
  
  <p>When I call <code>w-&gt;render(painter, w-&gt;mapToGlobal(QPoint(0,0))</code>, I get a bunch of controls all overlapping each other.<br>
  <code>w-&gt;layout()-&gt;activate();w-&gt;layout()-&gt;update()</code> doesn't seem to do anything.</p>
  
  <p>Is there a way to force the layout to happen without showing w?</p>