title: setGeometry() right after addWidget() issue
body: <p>I'm having troubles setting dimensions of a child-QWidget right after it is  added to a parent-QWidget.
  The issue is that it simply doesn't set the geometry:</p>
  
  <pre><code>from PyQt4 import QtCore, QtGui
  
  class MyWidget(QtGui.QWidget):
  
      def __init__(self):
  
          super(MyWidget, self).__init__()
  
          self.initUI()
  
  
      def initUI(self):
  
          # setting up parent QWidget
          self.setMinimumSize(256, 256)
          self.setMaximumSize(256, 256)
          self.GL = QtGui.QGridLayout(self)
          self.GL.setMargin(0)
  
          # setting up child QWidget
          self.GL.myWidget2 = QtGui.QFrame()
          self.GL.myWidget2.setMinimumSize(128, 128)
          self.GL.myWidget2.setMaximumSize(128, 128)
          self.GL.myWidget2.setStyleSheet("background: orange")
  
          # attaching child to parent
          self.GL.addWidget(self.GL.myWidget2)
  
          # trying to reposition child in parent's local space
          self.GL.myWidget2.setGeometry(QtCore.QRect(0, 128, self.width(), self.height()))
  
  
  
  if __name__ == '__main__':
      app = QtGui.QApplication(sys.argv)
      widget = MyWidget()
      widget.show()
      app.exec_()
  </code></pre>
  
  <p>Adding a timer that sets the geometry after a short delay does work though... (replacing <code>self.GL.myWidget2.setGeometry([...])</code> with):</p>
  
  <pre><code>        timer = QtCore.QTimer()
          timer.singleShot(10, self.updatePosition)
  
      def updatePosition(self):
  
          self.GL.myWidget2.setGeometry(QtCore.QRect(0, 128, self.width(), self.height()))
  </code></pre>
  
  <p>...so I suspect the addWidget(...) method to be doing a callback e.g. that redraws the widget in its default position while the main thread has already passed the <code>self.GL.myWidget2.setGeometry([...])</code> line.</p>
  
  <p>This is purely speculative though, any inside into how <code>addWidget()</code> affects following coder or execution timing would be much appreciated!</p>