title: Need to use TkApp backend with matplotlib in Pyzo
body: <p>I'm trying to put a live mass spectrum plot into a program that I am writing.  So far I have a simple GUI that give the program its basic functionality.  I also want it to have a live plot of a mass spectrum, a fairly simple 2D bar chart with about 10,000 peaks.  I'd like the user to be able to zoom and pan around the plot but the default backend of matplotlib is really slow.  I've been reading around and other backends are available and TkApp is recommended.  I also want it to be compatible with tkinter Python 3.3.  </p>
  
  <p>When I try to change the backend:</p>
  
  <pre><code>import matplotlib as mpl
  import matplotlib.pyplot as plt
  import numpy
  
  print(mpl.pyplot.get_backend())
  
  mpl.pyplot.switch_backend('TkAgg')
  
  plot = plt.plot([1, 2, 3, 4, 5, 6])
  plt.show(plot)
  
  print(mpl.pyplot.get_backend())
  </code></pre>
  
  <p>Output:</p>
  
  <pre><code>C:\pyzo2013c\lib\site-packages\matplotlib\mathtext.py:46: UserWarning: Due to a bug in pyparsing &lt;= 2.0.0 on Python 3.x, packrat parsing has been disabled.  Mathtext rendering will be much slower as a result.  Install pyparsing 2.0.0 or later to improve performance.
    warn("Due to a bug in pyparsing &lt;= 2.0.0 on Python 3.x, packrat parsing "
  Qt4Agg
  Traceback (most recent call last):
    File "C:\MyPyProgs\Sequencer\spectrum_plot.py", line 7, in &lt;module&gt;
      mpl.pyplot.switch_backend('TkAgg')
    File "C:\pyzo2013c\lib\site-packages\matplotlib\pyplot.py", line 124, in switch_backend
      _backend_mod, new_figure_manager, draw_if_interactive, _show = pylab_setup()
    File "C:\pyzo2013c\lib\site-packages\matplotlib\backends\__init__.py", line 28, in pylab_setup
      globals(),locals(),[backend_name],0)
    File "C:\pyzo2013c\lib\site-packages\matplotlib\backends\backend_tkagg.py", line 11, in &lt;module&gt;
      import matplotlib.backends.tkagg as tkagg
    File "C:\pyzo2013c\lib\site-packages\matplotlib\backends\tkagg.py", line 2, in &lt;module&gt;
      from matplotlib.backends import _tkagg
  ImportError: cannot import name _tkagg
  </code></pre>
  
  <p>I'm using the Pyzo package.  A couple of recommendations as fixes are to install python3-matplotlib-tk however it cannot find pyzo as it's a stand alone installation of python so is not in the registry.  Any help would be much appreciated.</p>
  
  <p>Thanks</p>