- If you want to know for certain. Download Snoop it has a 3d view that you can use to see every element that is rendered. (on and off screen) If your list box is not virtualised you will see all the list items marching off the page in a lovely 3d view.
It is an essential tool for the wpf developer as it has a couple of other really handy features as well
- Get rid of that list box template that uses a stack panel. If all it is doing is making the background black, then just set the background black.