/// <summary>
 /// Initializes a new instance of the 
 /// <see cref="PickerAutomationPeer"/> class.
 /// </summary>
 /// <param name="owner">The Picker that is associated to this 
 /// AutomationPeer.</param>
 protected PickerAutomationPeer(Picker owner)
     : base(owner)
 {
 }
        /// <summary>
        /// IsDropDownOpenProperty property changed handler.
        /// </summary>
        /// <param name="d">Picker that changed its IsDropDownOpen.</param>
        /// <param name="e">Event arguments.</param>
        private static void OnIsDropDownOpenPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            Picker source = (Picker)d;

            // Ignore the change if requested
            if (source._ignorePropertyChange)
            {
                source._ignorePropertyChange = false;
                return;
            }

            bool oldValue             = (bool)e.OldValue;
            bool newValue             = (bool)e.NewValue;
            bool delayedClosingVisual = source._popupClosedVisualState;
            RoutedPropertyChangingEventArgs <bool> args = new RoutedPropertyChangingEventArgs <bool>(e.Property, oldValue, newValue, true);

            PickerAutomationPeer peer = FrameworkElementAutomationPeer.FromElement(source) as PickerAutomationPeer;

            if (peer != null)
            {
                peer.RaiseExpandCollapseAutomationEvent(oldValue, newValue);
            }

            if (newValue)
            {
                // Opening
                source.OnDropDownOpening(args);

                // Opened
                if (!args.Cancel)
                {
                    source.OpenDropDown(oldValue, newValue);
                }
            }
            else
            {
                // Closing
                source.OnDropDownClosing(args);

                // Immediately close the drop down window:
                // When a popup closed visual state is present, the code path is
                // slightly different and the actual call to CloseDropDown will
                // be called only after the visual state's transition is done
                if (!args.Cancel && !delayedClosingVisual)
                {
                    source.CloseDropDown(oldValue, newValue);
                }
            }

            // If canceled, revert the value change
            if (args.Cancel)
            {
                // source._ignorePropertyChange = true;
                source.SetValue(e.Property, oldValue);
            }

            // Closing call when visual states are in use
            if (delayedClosingVisual)
            {
                source.UpdateVisualState(true);
            }
        }