title: Using matplotlib Cursor widget in GUI embedded plot
body: <p>I've got a PyQt4 GUI which has a matplotlib plot embedded in it. I want to add a <code>Cursor</code> widget (<a href="http://matplotlib.org/1.5.1/examples/widgets/cursor.html" rel="nofollow noreferrer">much like this example</a>, which does work for me) to the plot. For some reason, the Cursor doesn't show up in my embedded plot. What's going on?</p>
  
  <p>Below is a minimum (non-)working example.</p>
  
  <pre><code>import sys
  from PyQt4 import QtGui
  
  from matplotlib.backends.backend_qt4agg import FigureCanvasQTAgg as FigureCanvas
  from matplotlib.backends.backend_qt4agg import NavigationToolbar2QT as NavigationToolbar
  import matplotlib.pyplot as plt
  from matplotlib.widgets import Cursor
  
  import random
  
  class Window(QtGui.QDialog):
      def __init__(self, parent=None):
          super(Window, self).__init__(parent)
  
          plt.style.use('ggplot')
          self.figure = plt.figure()
          self.canvas = FigureCanvas(self.figure)
  
          self.toolbar = NavigationToolbar(self.canvas, self)
          #self.toolbar.hide()
  
          # Just some button 
          self.button = QtGui.QPushButton('Plot')
          self.button.clicked.connect(self.plot)
  
          # set the layout
          layout = QtGui.QVBoxLayout()
          layout.addWidget(self.toolbar)
          layout.addWidget(self.canvas)
          layout.addWidget(self.button)
          self.setLayout(layout)
  
      def plot(self):
          ''' plot some random stuff '''
          data = [random.random() for i in range(25)]
          ax = self.figure.add_subplot(111)
          ax.hold(False)
          ax.plot(data, '*-')
          Cursor(ax, lw = 2)
          self.canvas.draw()
  
  if __name__ == '__main__':
      app = QtGui.QApplication(sys.argv)
  
      main = Window()
      main.setWindowTitle('Simple QTpy and MatplotLib example with Zoom/Pan')
      main.show()
  
      sys.exit(app.exec_())
  </code></pre>