title: Qt QPropertyAnimation for widgets in layout - widgets shaking
body: <p>I want to make widgets increase in height with QPropertyAnimation, when widgets are arranged with QVboxLayout.
  The problem is that when I open more than one widget, they start to move/shake during animation.</p>
  
  <p>I have prepared minimum working example, here <a href="https://ufile.io/a4f29" rel="nofollow">tar gz project</a>
  The problem appears when you press "open" button for first, second, then third widget, you can see then that they are shaking, moving slightly up and down during "open" animation.</p>
  
  <p>Has someone idea what to do to avoid this ?
  I can set setSizeConstraint(QLayout::SetFixedSize) on main layout and they dont shake, but then resizing and other doesn't work.</p>
  
  <p>Best Regards</p>
  
  <p>Marek</p>