Reference TWSOpenGLWindow

  TWSOpenGLWindow = class(TWSWinControl)
  published
    class function CreateHandle(const AWinControl: TWinControl; const AParams: TCreateParams): HWND; override;
    { The native window of the control which the SDL window is placed inside, or
      0 if there is none }
    class function NativeWindow(AWinControl: TWinControl): PtrUInt;
    { The native window of the form holding the control, which has the keyboard
      focus of the window system while the form is active }
    class function TopLevelWindow(AWinControl: TWinControl): PtrUInt;
  end;