The engine treats GUITextWindowEdges as GUIButtons, and they need to be written to the game data file as the same type. For consistency with other GUIControl types, there are no public constructors for this type. Instead you must use a cast on a GUIControl to this type (the as operator may not be used because it does not support user-defined conversions). If a GUIControl that is neither a GUIButton nor a GUITextWindowEdge is cast to this type then null is returned.
