title: Retrieve the -data field of Tk virtual events in python event handeler
body: <p>Tcl/Tk allows for the generation of virtual events via the following syntax:</p>
  
  <pre><code>event generate .myWidget &lt;&lt;whatever&gt;&gt; -data "arbitrary text here"
  </code></pre>
  
  <p>A Tcl/Tk handle bound to this event would allow one to access the value of the <code>-data</code> option via the <code>%d</code> substitution.  From python, I can bind to this event:</p>
  
  <pre><code>def on_whatever(event):
      print("Meh")
  
  myWidget.bind("&lt;&lt;whatever&gt;&gt;", on_whatever, add="+")
  </code></pre>
  
  <p>This works fine for me up to this point, but I can not find any way from python to access the tcl/tk event's <code>-data</code> field.</p>