WpfWatermarkTextBox.Behaviors.WatermarkComboBoxBehavior.OnEnableWatermarkChanged C# (CSharp) Метод

        private static void OnEnableWatermarkChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            if (e.OldValue != null)
            {
                var enabled = (bool)e.OldValue;

                if (enabled)
                {
                    var comboBox = (ComboBox)d;
                    var behavior = GetWatermarkComboBoxBehavior(comboBox);
                    behavior.Detach();

                    SetWatermarkComboBoxBehavior(comboBox, null);
                }
            }

            if (e.NewValue != null)
            {
                var enabled = (bool)e.NewValue;

                if (enabled)
                {
                    var comboBox = (ComboBox)d;
                    var behavior = new WatermarkComboBoxBehavior(comboBox);
                    behavior.Attach();

                    SetWatermarkComboBoxBehavior(comboBox, behavior);
                }
            }
        }