Add several new tests to verify that Qt behaves properly when
high-DPI scaling is enabled. Add a generic framework for
manual tests for good measure. This could be refactored and
used for other manual tests later.
Includes tests written by Morten and Friedemann.
Task-number: QTBUG-46615
Change-Id: Ib6762ec1454711e71f0c094b19015932b99e8d6d
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@theqtcompany.com>
