Why does ItemContainerGenerator return null?

Question

I have a ListBox, and I need to set its ControlTemplate to a Virtualizing WrapPanel which is a class that extends VirtualizingPanel, using a style that looks like this:

Answer 1

For Windows 8.1 Metro apps, the ItemContainerGenerator was depricated and will return null. New Apis:

ItemsControl.ItemContainerGenerator.ItemFromContainer = ItemsControl.ItemFromContainer

ItemsControl.ItemContainerGenerator.ContainerFromItem = ItemsControl.ContainerFromItem

ItemsControl.ItemContainerGenerator.IndexFromContainer = ItemsControl.IndexFromContainer

ItemsControl.ItemContainerGenerator.ContainerFromIndex = ItemsControl.ContainerFromIndex

http://msdn.microsoft.com/en-us/library/windows/apps/dn376326.aspx