Tristan Van Berkom authored Aug 31, 2016 and Matthias Clasen committed Aug 31, 2016

Making propagation of child natural sizes mandatory (or default, even) was
evidently a mistake as this causes dynamic content in a scrolled window
to resize it's parent when the scrolled window is competing for space
with an adjacent widget.

This patch instead adds API to control whether natural width and
height of the child should be propagated through the scrolled windows
size requests.