If you are working with Telerik RadListBox for Silverlight or WPF and if you upgraded your Telerik version to the Q1 2013 , you probably noticed that there is something wrong with it.
Basically the problem is when SelectedIndex is changed , the SelectedItem property is not updated and vice versa.
A classic scenario is when you try to set a by default selection:
_myListBox.SelectedIndex = 0;
If(_myListBox.SelectedItem != null)
This is not working anymore with Telerik Q1 2013 because SElectedItem is not updated.
What you can do is instead of _myListBox.SelectedIndex = 0;
put _myListBox.SetValue(RadListBox.SelectedItemProperty, _myListBox.Items);