Hello, how do I get the last selected item in a ListBox?

The user is able to select multiple items in the listbox, but I want to know which item the user selected last. I am using ListBox.SelectedItems to get the array of items selected, I thought I could just check the last item in the array, but it doesn't work like that. The last item in the array is not the last item selected. It doesn't add on values to the array, it simply checks off which item has been selected..

I was looking on MSDN and I couldn't find anything.. Does anyone know of a way to do this?