Hi John;

  The key here ( and I would recommend that all tab pages be created this way)   ...

1. Create a Custom Visual User Object
2. Add your controls as required
3. In the CVUPO properties pane, set the scrollbar properties as required & save it
4. In the Tab Control, add the Tab Page as a User Object (never use "new" option).

Using the above method, your tab pages have more control and they always then have a common ancestor.  ;-)

HTH

Regards ... Chris

Please see if this Q&A post will help you:

    https://community.appeon.com/index.php/qna/q-a/how-to-scroll-vertically-on-user-object-using-powerscript

That thread contains an example application that illustrates one way a scrollbar can be used to scroll the contents of a custom visual user object.

I have difficulty imagining myself using an app where 15 DataWindows reside within a single tab page, let alone coding it. This does not sound like an effective or optimal user interface.