System.Windows.Controls.SelectorSelectionAdapter.SelectedIndexDecrement C# (CSharp) Method

        protected void SelectedIndexDecrement()
        {
            if(SelectorControl != null)
            {
                int index = SelectorControl.SelectedIndex;
                if(index >= 0)
                {
                    SelectorControl.SelectedIndex--;
                }
                else if(index == -1)
                {
                    SelectorControl.SelectedIndex = SelectorControl.Items.Count - 1;
                }
            }
        }