Description of the new feature/enhancement

The TabView currently stops after the add button. This is a problem because it has a shadow which gets interrupted.
It's harder to see with the default gray titlebar, but if you could change it to white it would be noticeable.

It would be ideal if the TabView would span the entire window.

Proposed technical implementation details

It can be achieved by moving the drag bar and caption buttons inside the TabStripFooter.