title: WPF floating listbox
body: <p>I have a textbox that I would like to combine with a listbox in such a way that when the user types into the textbox, certain items will appear in the listbox, and the user may select them from there.  What I am looking for is behaviour similar to that of the AutoCompleteBox.  Sadly, I can't use the existing AutocompleBox in my project for several reasons, so I am trying to come up with similar behaviour on my own.  Any ideas?</p>
  
  <p>EDIT:
  I would like to avoid using the tooltip as this seems like a hack.  Also, when the listbox is displayed, no layouts should be changed either in the control or elsewhere.   Is there something like the CSS style overflow available?</p>