title: Implementing JavaScript callback for checkboxes in bokeh?
body: <p><strong>Short version:</strong> bokeh checkboxes with JS callbacks to plot subsets of a dataframe?</p>
  
  <p><strong>Longer version:</strong>  The answer <a href="https://stackoverflow.com/questions/56187774/how-to-implement-a-javascript-callback-for-a-multiselect-widget-in-bokeh">here</a> gives a good explanation for multiselect, but I want to do the same thing for checkboxes.  All my data is in one pandas dataframe, and I'm using the checkboxes to select bits of that dataframe for plotting.  I believe that with checkboxes it is something to do with <code>cb_obj.active</code> but I'm very unsure how to get it to work.  In particular my plot includes colored rectangles and text, all information for which: position, text, color, is taken from my dataframe.  And I don't know how much plotting must be done in the callback, and how much outside.  </p>
  
  <p>As far as I can tell, the callback calls a function to do the actual plotting.</p>
  
  <p>I know I should give a minimal example, but I can't think how to simplify my code enough... so all I really want at the moment is an example of the use of checkboxes, with a JavaScript callback, to plot a subset of a dataframe.  Somebody must have done this, but I haven't found an example yet!  Thanks.</p>