public override void Update(GameTime gameTime)
        {
            if (InputHelper.InputCancelPressed())
            {
                RemoveScreen(this);
            }
            else if (InputHelper.InputConfirmPressed() && ListPresentUnit.Count > 0)
            {
                GameScreen CustomizeScreen = SelectedUnit.GetCustomizeScreen();

                if (CustomizeScreen == null)
                {
                    CustomizeScreen = new DefaultUnitUpgradesScreen(SelectedUnit, ActiveParser);
                }

                PushScreen(CustomizeScreen);
            }
            else
            {
                UnitSelectionMenu.Update(gameTime);
            }
        }