title: How to make widgets automatically stretch to the parent widget's size in Qt Designer
body: <p>I need to add a <code>TabWidget</code> control to the <code>MainWindow</code> and place <code>TableWidget</code> in every tab it has. The problem is that I need to make them automatically stretch to the parent widget's size (<code>TabWidget</code> to the window's size, <code>TableWidget</code>'s to the <code>TabWidget</code>'s size).</p>
  
  <p>What is the easiest way to achieve it via Qt Designer?</p>