This is an update on a separate post in another forum.
http://www.telerik.com/community/forums/silverlight/general-discussions/selectedindex-update-selecteditem-in-radlistbox-in-raddropdownbutton.aspx
I have looked into this a little more and it is not the fault of the RadDropDownButton. This issues seems to pertain to the RadListBox itself. The RadListBox will not change the SelectedItem when you change the SelectedIndex if it has not been shown at least once. Once it is loaded for the first time it can be unloaded and works fine. I have modified the original application to show this behavior.
In the demo you will notice when you start the application clicking the buttons does not cause the SelectedItem to change. Once you Toggle Visibility it will work from that point on. It even continues working when the ListBox is hidden again.
This problem only exists in the latest build of Telerik. I have tested it on the last build and it works as expected. The regular ListBox also doesn't have the issue.
I thought maybe there was something going on with virtualization here but I replaced the VirtualizingStackPanel with a regular StackPanel and that didn't help.
New test project
http://dl.dropbox.com/u/59731064/RadDropdownTestProject2.zip
http://www.telerik.com/community/forums/silverlight/general-discussions/selectedindex-update-selecteditem-in-radlistbox-in-raddropdownbutton.aspx
I have looked into this a little more and it is not the fault of the RadDropDownButton. This issues seems to pertain to the RadListBox itself. The RadListBox will not change the SelectedItem when you change the SelectedIndex if it has not been shown at least once. Once it is loaded for the first time it can be unloaded and works fine. I have modified the original application to show this behavior.
In the demo you will notice when you start the application clicking the buttons does not cause the SelectedItem to change. Once you Toggle Visibility it will work from that point on. It even continues working when the ListBox is hidden again.
This problem only exists in the latest build of Telerik. I have tested it on the last build and it works as expected. The regular ListBox also doesn't have the issue.
I thought maybe there was something going on with virtualization here but I replaced the VirtualizingStackPanel with a regular StackPanel and that didn't help.
New test project
http://dl.dropbox.com/u/59731064/RadDropdownTestProject2.zip