title: QWidget not updating/repainting consistently
body: <p>I'm building a CAD-like application, when the viewport object selection changes a signal is emitted containing a QHash of the new objects.  This signal is caught by it's document sub window which lifts the new properties/settings UI out of them, destroys the existing properties display in the main window properties pane, and replaces them with the new properties/settings.</p>
  
  <p>Using print statements, I know that this works - all the signal/slot connections are firing correctly.  However, the properties widgets are very inconsistently repainted, if I perform an operation on the main window directly (press a button, hover the mouse over a widget) the widgets in question update.  But when I'm just selecting objects in the viewport, the properties pane 'misses' an update so it ends up displaying the previous object's properties - I know this is not a problem on my end because if I move the window or interact with the widgets (to trigger a repaint), the widgets magically become correct.</p>
  
  <p>These functions are not being called from separate threads.  If I manually call update() in my code, nothing changes.  If I call repaint() directly (I know I shouldn't) it works a little better, but it's a bit unstable - sometimes the widgets are not drawn at all.</p>
  
  <p>Has anyone had a similar experience?</p>