Graphics.RestoreState does not consistently restore drawing properties

Graphics.RestoreState() does not consistently restore mutable drawing properties such as Opacity to the values captured by the matching Graphics.SaveState(). The drawing renderer and the readable Graphics properties can therefore disagree after leaving a saved drawing scope, and code that reads or adjusts those properties may draw with an unexpected state. Saving and restoring graphics state should cover every mutable setting that affects subsequent drawing, as well as transforms and clipping, including when save scopes are nested.