title: Set selected TreeItem in TreeView
body: <p>I have a TreeView that is inside a GridPane. A certain function requires the user to select a TreeItem and click on button on the screen. After the function associated with the button is completed, I want the focus to go back to the TreeItem that was previously selected in the TreeView. </p>
  
  <p>At the end of the button action, I have:</p>
  
  <p><code>TreeItem&lt;String&gt; selectedItem = [TreeItem that was last selected]</code> </p>
  
  <p>How can I give focus back to the TreeView with <code>selectedItem</code> highlighted?</p>
  
  <p>Neither the TreeView or TreeItem have a <code>setSelected</code> method I can use.</p>