Currently, when driving a TabControl with Data, the ItemContainer and Item Templates function as expected.
However, the TabControl's 'Content' Template seems to initially be broken at creation, offering no Elements of functionality that can be leveraged until the Template is exited and re-entered.

Repro Steps:

1) Create a Studio Project containing a MainPage.xaml

2) Navigate to the Data Panel, and create a Data Structure named 'Tab", containing two 'String' Properties "TabName" and "TabContent", each set as 'Singles'.
3) Still within the Data Panel, create a second Data Structure named 'ViewModel', containing a Property named "TabCollection", serving the "Tab" Structure from Step 2, and set to serve as a 'Collection'.
4) Create a Data Set for the 'ViewModel' Structure, populate it with random Sample Data, and apply the DataSet to the Page.

At this point, the DataSet should be populated with a collection of items, with random values for both the 'TabName' and 'TabContent' fields for each item in the Collection.

5) Select the TabControl on the Page, navigate to its Properties Panel, and set its 'Items Source' Property to be bound to the Data applied to the 'TabCollection' DynamicCollection.

6) Right-Click on the TabControl, navigate to Templates-->Content-->Create.
This will open the 'Content' Template in the Template Dummy Editor.

Observe how the Template contains no Elements in the Navigator, and offers no usable functionality of customization.

7) Exit the 'Content' Template in the Template Dummy Editor, and return to the Page.

8) Once again,right-Click on the TabControl, navigate to Templates-->Content-->Create.
This will open the 'Content' Template in the Template Dummy Editor.

Observe how now, the Template features Elements visible in the Navigator.

Expected Results: The TabControl's 'Content' Template presents a fully-functional Template internal structure upon creation.