title: On Mouse-hover on a data point on scatter matplotlib plot, show label
body: <p>I have a data set in the form of: </p>
  
  <pre><code>data = [('name1','value1','factor1')...[('nameN','valueN','factorN')]
  </code></pre>
  
  <p>I am trying to plot values as y (x is just the index of that y in data). I want matPlotLib to print the corresponding name and factor of the value on which the mouse pointer hovers. 
  I found one example of that implemented but it used wxPython and unfortunately I can't use that. Any way to do that ( including if name can be shown in the toolbar of matplotlib or just appear as a label on the point and disappear upon moving away of the pointer) would be very helpful.  </p>