Always request natural size inside Gtk::ScrolledWindows
Until Gtk 3.20 GtkScrolledWindow allocated natural size to its children. In Gtk 3.22 this was changed and GtkScrolledWindow instead requests minimum size to its children. This was done because it is somewhat safer (has a better behaviour) in case of dynamic content inside the scrolled window. If content is not dynamic then it is better to request the natural size, and an API was added for this.
This patch makes the layout consistent on all Gtk3 versions and makes the layout better looking on Gtk3 3.22+
|w/out patch||with patch|