title: Tooltips not showing up on Ubuntu using PyQt4
body: <p>I'm getting started with PyQt4 and tested the following code...</p>
  
  <pre><code>import sys
  from PyQt4 import QtGui
  from PyQt4 import QtCore
  
  
  class Tooltip(QtGui.QWidget):
      def __init__(self, parent=None):
          QtGui.QWidget.__init__(self, parent)
  
          self.setGeometry(300, 300, 250, 150)
          self.setWindowTitle('Tooltip')
  
          self.setToolTip('This is a &lt;b&gt;QWidget&lt;/b&gt; widget')
          QtGui.QToolTip.setFont(QtGui.QFont('OldEnglish', 10))
  
  
  app = QtGui.QApplication(sys.argv)
  tooltip = Tooltip()
  tooltip.show()
  sys.exit(app.exec_())
  </code></pre>
  
  <p>However, no tooltip shows up! I'm on Ubuntu 10.04. I also tried an icon and that didn't work either.</p>