title: How to wire path/chart redraw after y domain changes
body: <p>I want to draw multiple barcharts into the same visualization.</p>
  
  <p>When the first barchart is drawn it ḱnows nothing about the domain of the 2nd, 3rd, etc. At the time the 2nd barchart is drawn the domain of the y scale changes. 'Consequently the first barchart needs to be redrawn. The question is what is a good way to wire up the redraw since the scale/domain has no change notification mechanism.</p>
  
  <p><a href="http://bl.ocks.org/markfink/4d8f1c183e6cd9d6ea07" rel="nofollow">http://bl.ocks.org/markfink/4d8f1c183e6cd9d6ea07</a></p>