title: Matplotlib: Finding out xlim and ylim after zoom
body: <p>you for sure know a fast way how I can track down the limits of my figure after having zoomed in? I would like to know the coordinates precisely so I can reproduce the figure with <code>ax.set_xlim</code> and <code>ax.set_ylim</code>.
  I am using the standard qt4agg backend.</p>
  
  <p>edit: I know I can use the cursor to find out the two positions in the lower and upper corner, but maybe there is formal way to do that?</p>