Part 3: In this stream, we create a custom region behavior that allows us to inject ribbon tab items into the Infragistics xamRibbon control region depending on what view we navigated to in the ContentRegion. This is the mechanism that will allow our ribbon tabs to change depending on the view we are currently on. For example, when we navigate to the MailList, we will get the ribbon tabs associated with email. When we navigate to the Contacts view, we get the ribbon tabs associated with contacts. We also see how we can invoke commands from the ribbon tab items that are defined on the views ViewModel by modifying our DependentViewRegionBehvaior to allow us to share the DataContext between the RibbonTabItems and the views.