title: JavaFX - move TreeItem up down in TreeView
body: <p>I have a tree view that looks like this.</p>
  
  <pre><code>-Root
  --Parent 1
  ----Child 1
  ----Child 2
  ----Child 3
  --Parent 2
  ----Child 1
  ----Child 2
  </code></pre>
  
  <p>I've looked all over SO and Google but I can't find a proper way to move TreeItems up and down in the tree list. Is this possible? </p>
  
  <p>I'm not talking about just moving the <code>child</code> nodes, rather when I move the parents up, I need the children to move with them as well. So moving <code>Parent 2</code> up would look like this.</p>
  
  <pre><code>-Root
  --Parent 2
  ----Child 1
  ----Child 2
  --Parent 1
  ----Child 1
  ----Child 2
  ----Child 3
  </code></pre>