Bug#636620: gir1.2-gtk-3.0: No way to get a style property in python

[Daniel Trebbien]

To get a style property, you now need to pass in a Value object (which
wraps a GValue).  Here, for example, is PyGObject code to access the
"shadow-type" style property of `widget`:

    shadow_type_val = GObject.Value()
    shadow_type_val.init(Gtk.ShadowType)
    widget.style_get_property("shadow-type", shadow_type_val)
    self.frame.set_shadow_type(shadow_type_val.get_enum())

There are more examples of accessing Gtk.Widget style properties at:
http://consciouslyusing.blogspot.com/2012/01/coding-aligning-widgets-with.html

Daniel Trebbien