ARCed.Database.Troops.TroopMainForm.ButtonAddEnemyClick C# (CSharp) Method

        private void ButtonAddEnemyClick(object sender, EventArgs e)
        {
            var index = this.listBoxEnemies.SelectedIndex;
            if (index >= 0)
            {
                var sprite = new EnemySprite(Project.Data.Enemies[index + 1]);
                this.xnaPanel.AddSprite(sprite);
            }
            if (this.xnaPanel.Sprites.Count >= 12)
                this.buttonAddEnemy.Enabled = false;
        }