title: Zoomable treemap with tooltips at the bottom
body: <p>The <a href="http://mbostock.github.io/d3/talk/20111018/treemap.html" rel="nofollow noreferrer">zoomable treemap</a> is great, but there is one feature that I think would make it even greater. When hovering the mouse around the rectangles (either before or after zooming), there is no easy way to know where in the hierarchy the rectangle is, and what its size is.</p>
  
  <p>I am new to D3, but am wondering what changes I would need to make to have a hovering tooltip like the one shown below working. Is this a relatively easy fix, or would it take a big change to the source code to have it? Where could I get started?</p>
  
  <p><img src="https://i.stack.imgur.com/LdczL.png" alt="enter image description here"></p>