title: Use both matplotlib inline and qt in jupyter notebook
body: <p>I am using Jupyter (with IPython) to analyze research data, as well as export figures. I really like the notebook approach offered by Jupyter: when I revisit an experiment after a long time, I can easily see how the figures correspond to the data. This is of course using the inline backend.</p>
  
  <p>However, when I want to explore new data, I prefer to use the QT backend. It is faster than the inline one, and allows to easily scale, zoom in and out, and nicely displays the X and Y coordinates in the bottom left corner. Moreover, I can use the QT backend to determine good x and y limits to use in the inline backend.</p>
  
  <p>I have tried using the <code>%matplotlib notebook</code> magic, but it is simply too slow. For some experiments I am plotting ~500 spectra (each consists of ~1000 data points), which is already slow in the inline backend. Even with less data points, the notebook backend is just too slow to use.</p>
  
  <p>Therefore, I would like to use both the QT backend, and the inline backend whenever I plot something. (So, whenever I execute a cell which plots data, it should both display the inline image, and pop up a QT backend window). This way, I still have a nice overview of plots in my notebook, while also allowing me to easily explore my data. Is there a way to achieve this?</p>