internal void UnregisterScreen(UIPanelController panelController)
 {
     panelControllers.Remove(panelController);
     panelControllersByPanelType.Remove(panelController.GetType());
 }
 internal void RegisterScreen(UIPanelController panelController)
 {
     panelControllersByPanelType.Add(panelController.GetType(), panelController);
     panelControllers.Add(panelController);
 }