WPF ListBox grouping with ExpressionDark theme

Question

I found this simple tutorial on grouping a listbox:

http://joyfulwpf.blogspot.com/2007/06/simple-grouping-in-listbox.html

It works perfectly well, but the application I want to use this in is using the ExpressionDark theme. With this theme enabled, I only see the group headers and not the items.

I can't find out what in the theme is causing this behaviour.

Could anyone help me?

Thanks!

Edit: "Solved" it by using a TreeView instead.

Answer 1

Edit: "Solved" it by using a TreeView instead.