Unlike the context returned by Widget.CreatePangoContext, this context is owned by the widget (it can be used until the screen for the widget changes or the widget is removed from its toplevel), and will be updated to match any changes to the widget's attributes.
If you create and keep a Pango.Layout using this context, you must deal with changes to the context by calling Pango.Layout.ContextChanged on the layout in response to the Widget.StyleSet and Widget.DirectionChanged events for the widget.