We have created a SDK sample with a CustomRegionAdapter for the RadTabControl in which the ActivateView logic is implemented. You can find the example in out SDK repository(https://github.com/telerik/xaml-sdk/tree/master/TabControl/PRISM/CustomTabControlRegionAdapter)

Create custom region adapter for the RadTabControl

We have created a SDK sample with a CustomRegionAdapter for the RadTabControl and its implementation can be found in out SDK repository(https://github.com/telerik/xaml-sdk/tree/master/TabControl/PRISM/CustomTabControlRegionAdapter)

Prism View is incorrectly initialized when associated with a region

We have created a SDK sample with a CustomRegionAdapter for the RadTabControl and its implementation can be found in out SDK repository(https://github.com/telerik/xaml-sdk/tree/master/TabControl/PRISM/CustomTabControlRegionAdapter)

Preserve the content of tabs during tab reorder

Loaded event of the RadTabItem's content is fired twice in WPF.

Declined: The behaviour is caused due to the way how the WPF framework operates with ContentControl and their Content property(the RadTabItem is HeaderedContentControl which derives from ContentControl). The Content property is automatically registered to the LogicalTree when it is set, this is causing the first loaded event to be fired. After a selection is made the RadTabControl inserts/visualizes the Content of its selected RadTabItem in its ContentPresenter, this causes the control to fire its loaded event as it is loaded into the VisualTree.

private void Content_Loaded(object sender, RoutedEventArgs e)
{
	if (VisualTreeHelper.GetParent(sender as DependencyObject) != null)
	{
		// Execute the logic for LoadedEvent.
	}
}

ItemsSource does not support CompositeCollection

Click event of a Button in the HeaderTemplate is not fired properly when another button outside the tab has IsDefault property set to true

When navigating with tab key (without setting tabindex) first highlights the RadTabItem then its content. Setting a tabindex on a control in the tabItem`s content works the opposite way

Fire the PreviewSelectionChanged event before user-initiated selection

Fixed in LIB version: 2014.3.1103

Scrolling in TabStrip does not work well when TabStripPlacement=Left or Bottom and  ScrollMode=Item. Pressing the Scroll Buttons scrolls the entire set of tabs.

When the RadTabControl AllowDragReorder property is set to True and the control contains multiple rows with tabs, the dragging operation cannot be properly executed and completed.

The TabItem doesn't changes when selected Item in the VS2010 designer.

UPDATE:
The issue is present also in the VS2008 and Blend.

In the VS2010 designer the selected tab is the last one even if the SelectedIndex proeprty of the TabControl is set to 0. The issue can be reprodiced in a scenario where the RadTabControl is defined in a RadWindow control.

Using Xaml declared tab control with identical tab item headers will result in selecting the first occurance of selected text from the drop down content.
Add support for distinguishing different items in the drop down content (use DropDownDisplayMode=Visible) during selection and match to the corresponding TabItem.

Pressing "Tab" key does not change the focus when there are several controls in a TabItem.

SelectedItem does not respect the Reset collection changed action.

ICommandSource implementation for RadTabControl. It might be implemented either as CLR and dependency properties, or as attached behavior.

The animation when moving tab is mandatory for a proper user experience.