title: QPushButton not displaying
body: <p>I started reading the zetcode tutorial for PyQt4 (<a href="http://zetcode.com/tutorials/pyqt4/firstprograms/" rel="nofollow">http://zetcode.com/tutorials/pyqt4/firstprograms/</a>) and I was doing the tooltip part and all I did was copy and paste this bit of code. When I went to run it, the push button did not display in the window. Any reason as to why this might be? new to PyQt4 and Qt in general.</p>
  
  <pre><code>import sys
  from PyQt4 import QtGui
  
  class Example(QtGui.QWidget):
  
      def __init__(self):
          super(Example, self).__init__()
  
          self.initUI()
  
      def initUI(self):
          QtGui.QToolTip.setFont(QtGui.QFont('SansSerif', 10))
  
          self.setToolTip('This is a &lt;b&gt;QWidget&lt;/b&gt; widget')
  
          btn = QtGui.QPushButton('Button, self')
          btn.setToolTip('This is a &lt;b&gt;QPushButton&lt;/b&gt; widget')
          btn.resize(btn.sizeHint())
          btn.move(50, 50)
  
          self.setGeometry(300, 300, 250, 150)
          self.setWindowTitle('Tooltips')
          self.show()
  
  def main():
      app = QtGui.QApplication(sys.argv)
      ex = Example()
      sys.exit(app.exec_())
  
  if __name__ == '__main__':
      main()
  </code></pre>