title: Python matplotlib, get position of xtick labels
body: <p>How do I get the positions of the xtick major labels?
  The values that I am getting from label.get_position() do not make sense. </p>
  
  <pre><code>import numpy as np
  import matplotlib.pyplot as plt
  
  def f(t):
      return np.exp(-t) * np.cos(2*np.pi*t)
  
  t1 = np.arange(0.0, 5.0, 0.1)
  t2 = np.arange(0.0, 5.0, 0.02)
  
  # fig, ax = plt.figure(1)
  fig, ax = plt.subplots()
  plt.plot(t1, f(t1), 'bo', t2, f(t2), 'k')
  
  # plt.show()
  print(fig)
  print(ax.get_position())
  
  # ------------------------------------------------
  # positions of the tick labels, incorrect (0,0) returned
  # ------------------------------------------------
  print([text.get_position() for text in ax.get_xticklabels()])
  # correct tick label values
  print(ax.get_xticks())
  </code></pre>
  
  <p>Output from the above code is:</p>
  
  <pre><code>Figure(640x480)
  Bbox('array([[ 0.125,  0.1  ],\n       [ 0.9  ,  0.9  ]])')
  [(0.0, 0.0), (0.0, 0.0), (0.0, 0.0), (0.0, 0.0), (0.0, 0.0), (0.0, 0.0)] &lt;-- incorrect positions
  [ 0.  1.  2.  3.  4.  5.]
  </code></pre>
  
  <p>How do I get the positions of the xtick major labels?
  The values that I am getting from label.get_position() do not make sense. Is there a transform that I don't know about?
  Ultimately I want the position of the text boxes in (x,y) image pixel units.</p>