TabbedPageScrollViewIssue

Demonstrates a scrolling issue with ScrollView / TabbedPage

To reproduce issue:

1. Reduce the height of the app so only Labels 1 to 10 are visible.
2. When I try to scroll, I can only scroll down to Label 11!
3. Slowly Change the width of the main window - you will see the vertical scrollbar change size! Sometimes it's too big to see the bottom of it, in which case you can't scroll to the bottom, but sometimes you CAN see a gap at the bottom, in which case you can scroll !
4. The page is now correctly scrollable down to the last label, Label 15!