title: Matplotlib in Spyder: plot shows immediately
body: <p>I'm trying to use the matplotlib.pyplot package in Spyder: everytime I plot something, as</p>
  
  <pre><code>plt.plot([1,2,3,4])
  </code></pre>
  
  <p>the plot shows immediately, without the call to .show(). This is bothering me, since if I make an adjustment, like</p>
  
  <pre><code>plt.ylab('try this')
  </code></pre>
  
  <p>it shows a brand new plot with the label but without the data.<br>
  What am I missing?</p>
  
  <p>Python 3.4.3<br>
  Spyder 3.0.0dev<br>
  Qt 5.5.1</p>