title: RuntimeError: Can not put single artist in more than one figure when using matplotlib 1.5
body: <p>Here is my code:</p>
  
  <pre><code>import matplotlib.pyplot as plt
  plt.figure(1)                # the first figure
  plt.subplot(211)             # the first subplot in the first figure
  plt.plot([1, 2, 3])
  plt.subplot(212)             # the second subplot in the first figure
  plt.plot([4, 5, 6])
  
  plt.figure(2)                # a second figure
  plt.plot([4, 5, 6])          # creates a subplot(111) by default
  plt.text(.5,1.5,'211',figure = 211) #tring to add text in previous subplot
  
  plt.figure(1)                # figure 1 current; subplot(212) still current
  plt.subplot(211)             # make subplot(211) in figure1 current
  plt.title('Easy as 1, 2, 3') # subplot 211 title
  </code></pre>
  
  <p>The error:</p>
  
  <pre><code>Traceback (most recent call last):
  File "C:/Users/ezhou/Desktop/python/test3.py", line 11, in &lt;module&gt;
  plt.text(.5,1.5,'211',figure = 211)
  File "C:\Python27\lib\site-packages\matplotlib\pyplot.py", line 3567, in text
  ret = gca().text(x, y, s, fontdict=fontdict, withdash=withdash, **kwargs)
  File "C:\Python27\lib\site-packages\matplotlib\axes\_axes.py", line 619, in text
  self._add_text(t)
  File "C:\Python27\lib\site-packages\matplotlib\axes\_base.py", line 1720, in _add_text
  self._set_artist_props(txt)
  File "C:\Python27\lib\site-packages\matplotlib\axes\_base.py", line 861, in _set_artist_props
  a.set_figure(self.figure)
  File "C:\Python27\lib\site-packages\matplotlib\artist.py", line 640, in set_figure
  raise RuntimeError("Can not put single artist in "
  RuntimeError: Can not put single artist in more than one figure
  </code></pre>
  
  <p>I was trying to understand the kwargs 'figure' in class matplotlib.text.Text(), but it will always reply 'Can not put single artist in more than one figure'. So I was confused about how to use this 'figure' kwarg. Can anyone give me some advise? Thanks! </p>