FIX: Ensure Window target surfaces are in sync when setting GUIContext.
FIX: Ensure Window target surfaces are in sync when setting GUIContext.

OpenTechEngine/CEGUI,ruleless/CEGUI,OpenTechEngine/CEGUI,ruleless/CEGUI,ruleless/CEGUI,OpenTechEngine/CEGUI,OpenTechEngine/CEGUI,ruleless/CEGUI