title: Command for clicking on the items of a Tkinter Treeview widget?
body: <p>I'm creating a GUI with Tkinter, and a major part of the GUI is two Treeview objects. I need the contents of the <code>Treeview</code> objects to <em>change</em> when an item (i.e. a directory) is <em>clicked twice</em>.</p>
  
  <p>If Treeview items were buttons, I'd just be able to set <code>command</code> to the appropriate function. But I'm having trouble finding a way to create <code>"on_click"</code> behavior for Treeview items.</p>
  
  <p>What Treeview option, method, etc, enables me to bind a command to particular items and execute that command <code>"on_click"</code>?</p>