The application attached can be used to reproduce the issue.

Steps to reproduce:
1. run the application on a touch device
2. touch the 'inactive' window with one finger (it becomes 'active')
3. touch the other window which is 'inactive' now, it becomes 'active'
4. repeat

Expected result:
The focus should change from one window to the other

Actual result:
After tapping few times, the focus doesn't change any more from window to window.

However, if one starts to tap with two fingers, then the focus changes correctly from window to window.