WIP: RFC: Refresh window shadows
Just something that arose from a discussion with Tobias, opening for further discussion.
These are basically elementary shadows ported to Adwaita. That includes: a larger shadow for active window, and a lot smaller shadows for tiled windows.
Other than that, I enabled normal->backdrop decoration transition too, not just backdrop->normal. (though maybe it was disabled because of performance concerns?)
Message dialogs, menus and popovers are unchanged.
