WPF: Cancel a user selection in a databound ListBox?

Question

How do I cancel a user selection in a databound WPF ListBox? The source property is set correctly, but the ListBox selection is out of sync.

I have an MVVM app that

Answer 1

In .NET 4.5 they added the Delay field to the Binding. If you set the delay it will automatically wait to update so there is no need for the Dispatcher in the ViewModel. This works for validation of all Selector elements like the ListBox's and ComboBox's SelectedItem properties. The Delay is in milliseconds.