title: PyQt4: Window shows up at another position after hide() and show()
body: <p>Using PyQt4, when I hide a window and show it afterwards, it appears at another position (at least here on Linux). Example code:</p>
  
  <pre><code>#!/usr/bin/python3
  
  from PyQt4.QtGui import *
  
  app = QApplication([])
  widget = QWidget()
  widget.setLayout(QVBoxLayout())
  label = QLabel()
  widget.layout().addWidget(label)
  
  def hideShow():
      widget.hide()
      widget.show()
  
  widget.layout().addWidget(QPushButton('Hide/Show', clicked = hideShow))
  widget.show()
  app.exec_()
  </code></pre>
  
  <p>The window disappears and appears, but a bit below and to the right of the original position. I think it's displaced by the size of the window manager's frame around the actual widget.</p>
  
  <p>How can I place the window at the exact position where it was? And why does it move at all? Shouldn't it stay where it is?</p>