title: How do I capture keystroke events in D3 force layout?
body: <p>I would like to respond to keystroke events directed at nodes in my force layout. I've tried adding all the variants of "keystroke", "keypress", "keyup", "keydown" that I could think of, but none of them is firing. My mouse events fire just fine. I couldn't find any keystroke events in the d3 source.... is there a way to capture key strokes?</p>
  
  <pre><code>        nodes.enter().append("circle")
              .on("click", function(d) { return d.clickHandler(self); })
              .on("mouseover", function(d) { return d.mouseOverHandler(self); })
              .on("mouseout", function(d) { return d.mouseOutHandler(self); })
              .on("keyup", function(d) { 
                  console.log("keypress", d3.event); // also tried "keyup", "keydown", "key"
              })
              .classed("qNode", true)
              .call(force.drag);
  </code></pre>