bool C4GraphicsSystem::ViewportNextPlayer()
	{
	// safety: switch valid?
	if ((!Game.C4S.Head.Film || !Game.C4S.Head.Replay) && !Game.GraphicsSystem.GetViewport(NO_OWNER)) return false;
	// do switch then
	C4Viewport *vp = GetFirstViewport();
	if (!vp) return false;
	vp->NextPlayer();
	return true;
	}