修改Aaron Zhou 的WPF ComboBox 与 MultiComboBox 有感

用VS2012 Profile 测试发现ComboBox 与 MultiComboBox的数据源OnDataSourceChanged事件中，this.Items.Add()方法被循环调用并且速度很慢，是界面加载的主要瓶颈

（居然不是访问服务！怒改！）

原来该对象的每一次变更都会触发OnCollectionChanged事件，并会通知前台界面重新渲染，速度很慢。改用中间变量再一次性赋值就可以了。

另外，在对MultiComboBox增加输入搜索功能时发现，自定义的依赖属性DataSource，尽管ViewModel中绑定的是ObservableCollection并用TwoWay的方式，只要对象是通过集合的Add/Remove方式改变，就不会获得PropertyChange通知。因为对象的引用并没有变化。

但默认的ComboBox的ItemSource是可以的。看了源码也终于理解了为什么ComboBox除了ItemSource为什么还要个Items对象。

原来ItemSource与数据源绑定后同时注册了OnCollectionChanged事件，该事件中会对Items对象重新赋值（一次性赋值），由于ItemSource与ViewModel的对象是同一对象，

所以不论是直接赋值还是Add/Remove，ItemSource都能捕获到ViewModel数据源的变化。

另一个改动是MultiComboBox的SelectedItems属性，需要其内部不论是直接赋值还是Add/Remove都要通知到ViewModel的数据源对象。由于不能控制ViewModel的编码，只能每次都重新赋值了

最后附上可搜索过滤的MultiCombox代码：

using Microsoft.Practices.Prism.Commands;
using Microsoft.Windows.Themes;
using System;
using System.Collections;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Collections.Specialized;
using System.ComponentModel;
using System.Globalization;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Input;

namespace Common.Controls.CustomControls
{
    public class CustomMultipleDropDownBox : ComboBox
    {

        #region UI Control Property

        protected ListBox MyListBox
        {
            get
            {
                return base.GetTemplateChild("MyListBox") as ListBox;
            }
        }

        /// <summary>
        /// Gets the text box in charge of the editable portion of the combo box.
        /// </summary>
        protected TextBox EditableTextBox
        {
            get
            {
                return base.GetTemplateChild("DisPlayTextBlock") as TextBox;
            }
        }


        private CheckBox SelectAllCheckBox { get; set; }

        #endregion

        #region Dependency Property
        private const string SelectAllItem = "Select All";
        private int TotalCount { get; set; }
        private List<ComboBoxNode> dataSourceNodeList { get; set; }
        public DelegateCommand<ComboBoxNode> CheckBoxSelectCommand { get; set; }
        public DelegateCommand ToggleButtonClickCommand { set; get; }

        #region DataSource
        public ObservableCollection<ComboBoxNode> NodeList
        {
            get { return (ObservableCollection<ComboBoxNode>)GetValue(NodeListProperty); }
            set { SetValue(NodeListProperty, value); }
        }

        public static readonly DependencyProperty NodeListProperty =
            DependencyProperty.Register("NodeList", typeof(ObservableCollection<ComboBoxNode>), typeof(CustomMultipleDropDownBox), new PropertyMetadata(null, null));


        #endregion

        #region SelectedItems && SelectedCount

        private IList m_selectedItemCollection;
        protected IList SelectedItemCollection
        {
            set
            {
                m_selectedItemCollection = value;
                if (value != null && m_selectedItemCollection is INotifyCollectionChanged)
                {
                    ((INotifyCollectionChanged)m_selectedItemCollection).CollectionChanged
                += new NotifyCollectionChangedEventHandler(OnSelectItemCollectionChanged);
                }
            }
        }
        public IList SelectedItems
        {
            get { return (IList)GetValue(SelectedItemsProperty); }
            set { SetValue(SelectedItemsProperty, value); }
        }

        // Using a DependencyProperty as the backing store for SelectedItems.  This enables animation, styling, binding, etc...
        public static readonly DependencyProperty SelectedItemsProperty =
            DependencyProperty.Register("SelectedItems", typeof(IList), typeof(CustomMultipleDropDownBox), new PropertyMetadata(null, new PropertyChangedCallback(OnSelectedItemsChanged)));

        /// <summary>
        /// change selected count when selected items changed
        /// </summary>
        /// <param name="d"></param>
        /// <param name="e"></param>
        private static void OnSelectedItemsChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            CustomMultipleDropDownBox c = d as CustomMultipleDropDownBox;
            c.SelectedItemCollection = c.SelectedItems;
            if (c.SelectedItems != null && c.SelectedItems.Count == 0)
                c.SelectedCount = null;
            else
                c.SelectedCount = c.SelectedItems.Count;

            c.ChangeNodeIsSelectedStatus();
        }

        private void OnSelectItemCollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
        {
            this.ChangeNodeIsSelectedStatus();
        }

        /// <summary>
        /// Used to inform IsMandatory trigger how many items has selected
        /// </summary>
        public int? SelectedCount
        {
            get { return (int?)GetValue(SelectedCountProperty); }
            set { SetValue(SelectedCountProperty, value); }
        }

        // Using a DependencyProperty as the backing store for SelectedCount.  This enables animation, styling, binding, etc...
        public static readonly DependencyProperty SelectedCountProperty =
            DependencyProperty.Register("SelectedCount", typeof(int?), typeof(CustomMultipleDropDownBox), new PropertyMetadata(null, new PropertyChangedCallback(OnSelectedCountChanged)));

        private static void OnSelectedCountChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            CustomMultipleDropDownBox c = d as CustomMultipleDropDownBox;

            if (e.NewValue != null && (int)e.NewValue == 0)
            {
                c.SelectedCount = null;
            }
        }
        #endregion

        #region SeparateString
        public string SeparateString
        {
            get { return (string)GetValue(SeparateStringProperty); }
            set { SetValue(SeparateStringProperty, value); }
        }

        // Using a DependencyProperty as the backing store for SelectedItems.  This enables animation, styling, binding, etc...
        public static readonly DependencyProperty SeparateStringProperty =
            DependencyProperty.Register("SeparateString", typeof(string), typeof(CustomMultipleDropDownBox), new PropertyMetadata(";"));
        #endregion

        #region ItemEnabledPath
        public string ItemEnabledPath
        {
            get { return (string)GetValue(ItemEnabledPathProperty); }
            set { SetValue(ItemEnabledPathProperty, value); }
        }

        // Using a DependencyProperty as the backing store for DropDownHeight.  This enables animation, styling, binding, etc...
        public static readonly DependencyProperty ItemEnabledPathProperty =
            DependencyProperty.Register("ItemEnabledPath", typeof(string), typeof(CustomMultipleDropDownBox), new PropertyMetadata(null));
        #endregion

        #region DropDown Height & Width
        public double DropDownHeight
        {
            get { return (double)GetValue(DropDownHeightProperty); }
            set { SetValue(DropDownHeightProperty, value); }
        }

        // Using a DependencyProperty as the backing store for DropDownHeight.  This enables animation, styling, binding, etc...
        public static readonly DependencyProperty DropDownHeightProperty =
            DependencyProperty.Register("DropDownHeight", typeof(double), typeof(CustomMultipleDropDownBox), new PropertyMetadata(0.0));


        public double DropDownWidth
        {
            get { return (double)GetValue(DropDownWidthProperty); }
            set { SetValue(DropDownWidthProperty, value); }
        }

        // Using a DependencyProperty as the backing store for DropDownWidth.  This enables animation, styling, binding, etc...
        public static readonly DependencyProperty DropDownWidthProperty =
            DependencyProperty.Register("DropDownWidth", typeof(double), typeof(CustomMultipleDropDownBox), new PropertyMetadata(0.0));
        #endregion

        #region DisplayText and ToolTip
        public string DisplayText
        {
            get { return (string)GetValue(DisplayTextProperty); }
            set { SetValue(DisplayTextProperty, value); }
        }

        // Using a DependencyProperty as the backing store for DisplayText.  This enables animation, styling, binding, etc...
        public static readonly DependencyProperty DisplayTextProperty =
            DependencyProperty.Register("DisplayText", typeof(string), typeof(CustomMultipleDropDownBox), new PropertyMetadata(null, new PropertyChangedCallback(OnDisplayTextChanged)));

        /// <summary>
        /// To control tooltip's content and can displayed when this property is changed
        /// </summary>
        /// <param name="d"></param>
        /// <param name="e"></param>
        private static void OnDisplayTextChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            CustomMultipleDropDownBox c = d as CustomMultipleDropDownBox;

            if (e.NewValue != null)
            {
                if (e.NewValue.ToString().Length > c.MaxLength)
                {
                    c.DisplayTextToolTip = true;
                }
                else
                {
                    c.DisplayTextToolTip = false;

                }
                c.Text = e.NewValue.ToString();
            }
            else
            {
                c.DisplayTextToolTip = false;
                c.Text = null;
            }

        }

        /// <summary>
        /// Set whether tooltip can displayed
        /// </summary>
        public bool DisplayTextToolTip
        {
            get { return (bool)GetValue(DisplayTextToolTipProperty); }
            set { SetValue(DisplayTextToolTipProperty, value); }
        }

        // Using a DependencyProperty as the backing store for DisplayTextToolTip.  This enables animation, styling, binding, etc...
        public static readonly DependencyProperty DisplayTextToolTipProperty =
            DependencyProperty.Register("DisplayTextToolTip", typeof(bool), typeof(CustomMultipleDropDownBox), new PropertyMetadata(false));

        public int MaxLength
        {
            get { return (int)GetValue(MaxLengthProperty); }
            set { SetValue(MaxLengthProperty, value); }
        }

        // Using a DependencyProperty as the backing store for MaxLength.  This enables animation, styling, binding, etc...
        public static readonly DependencyProperty MaxLengthProperty =
            DependencyProperty.Register("MaxLength", typeof(int), typeof(CustomMultipleDropDownBox), new PropertyMetadata(0));

        #endregion


        #endregion

        #region construtor
        static CustomMultipleDropDownBox()
        {
            DefaultStyleKeyProperty.OverrideMetadata(typeof(CustomMultipleDropDownBox), new FrameworkPropertyMetadata(typeof(CustomMultipleDropDownBox)));

        }
        public CustomMultipleDropDownBox()
        {
            this.DropDownWidth = 400;
            this.DropDownHeight = 150;
            this.MaxLength = 30;
            this.DisplayTextToolTip = false;
            TextCompositionManager.StartComposition(new TextComposition(InputManager.Current, this.EditableTextBox,string.Empty));
            CheckBoxSelectCommand = new DelegateCommand<ComboBoxNode>(CheckBoxClickCommandProcess);
            ToggleButtonClickCommand = new DelegateCommand(ToggleButtonClickCommandProcess);
            dataSourceNodeList = new List<ComboBoxNode>();
            NodeList = new ObservableCollection<ComboBoxNode>();
            this.Loaded += CustomMultipleDropDownBox_Loaded;
        }

        private void CustomMultipleDropDownBox_LostFocus(object sender, RoutedEventArgs e)
        {
            this.IsDropDownOpen = false;
        }

        protected override void OnPreviewKeyDown(System.Windows.Input.KeyEventArgs e)
        {
            if (e.Key == Key.Down)
            {
                if (!this.IsDropDownOpen)
                {
                    this.DisplayText = null;
                    this.NodeList = this.dataSourceNodeList.ToObservableCollection();
                    this.IsDropDownOpen = true;
                }
                //e.Handled = true;
            }
            base.OnPreviewKeyDown(e);
        }

        void CustomMultipleDropDownBox_Loaded(object sender, RoutedEventArgs e)
        {
            try
            {
                OnApplyTemplate();
                this.IsEditable = true;

                if (this.SelectedItems == null || this.SelectedItems.Count == 0)
                {
                    this.SelectedCount = null;
                }
                else
                {
                    this.SelectedCount = this.SelectedItems.Count;
                    this.DisplayText = GetSelectedText();
                    if (this.SelectedCount == this.TotalCount)
                    {
                        this.SelectAllCheckBox.IsChecked = true;
                    }
                }
            }
            catch (Exception)
            {

            }
        }

        protected override void OnDropDownClosed(EventArgs e)
        {
            base.OnDropDownClosed(e);
            DisplayText = this.GetSelectedText();
            var selectedItems = this.dataSourceNodeList.
                FindAll(p => p.IsSelected && p.Title != SelectAllItem).Select(p => p.Item).ToList();
            var list = this.SelectedItems.CreateNewInstance();
            foreach (var item in selectedItems)
            {
                list.Add(item);
            }
            this.SelectedItems = list;
        }

        //protected override void OnItemsSourceChanged(IEnumerable oldValue, IEnumerable newValue)
        //{
        //    base.OnItemsSourceChanged(oldValue, newValue);
        //    this.InitDataSourceToComboBoxNodeList();

        //    DisplayText = null;
        //    OnApplyTemplate();
        //}

        protected override void OnItemsChanged(System.Collections.Specialized.NotifyCollectionChangedEventArgs e)
        {
            base.OnItemsChanged(e);
            this.InitDataSourceToComboBoxNodeList();

            OnApplyTemplate();
        }

        public override void OnApplyTemplate()
        {
            base.OnApplyTemplate();

            if (this.MyListBox == null)
            {
                return;
            }

            if (this.NodeList == null)
            {
                return;
            }

            if (this.EditableTextBox != null)
            {
                this.EditableTextBox.PreviewKeyUp += EditableTextBox_PreviewKeyUp;
                this.EditableTextBox.TextChanged += new TextChangedEventHandler(EditableTextBox_TextChanged);
                this.EditableTextBox.GotFocus += EditableTextBox_GotFocus;
                this.EditableTextBox.MouseLeftButtonUp += EditableTextBox_MouseLeftButtonUp;
            }
        }

        void EditableTextBox_PreviewKeyUp(object sender, KeyEventArgs e)
        {
            TextBox text = sender as TextBox;
            this.FilterDataSourceByInputText(text.Text);
            if (!this.IsDropDownOpen)
                this.IsDropDownOpen = true;
        }

        void EditableTextBox_MouseLeftButtonUp(object sender, MouseButtonEventArgs e)
        {
            this.DisplayText = null;
            this.IsDropDownOpen = true;
        }

        private void EditableTextBox_GotFocus(object sender, RoutedEventArgs e)
        {
            this.DisplayText = null;
            this.IsDropDownOpen = true;
        }

        private void EditableTextBox_TextChanged(object sender, TextChangedEventArgs e)
        {
            TextBox text = sender as TextBox;
            this.FilterDataSourceByInputText(text.Text);
        }

        private void ToggleButtonClickCommandProcess()
        {
            this.DisplayText = null;
            this.IsDropDownOpen = true;
        }

        private void CheckBoxClickCommandProcess(ComboBoxNode node)
        {
            if (this.SelectedItems == null)
            {
                return;
            }

            if (node.Title == SelectAllItem)
            {
                foreach (var item in this.dataSourceNodeList)
                {
                    if (item.IsEnabled)
                        item.IsSelected = node.IsSelected;
                }
            }
            else
            {
                var selectAllItem = this.dataSourceNodeList.Find(p => p.Title == SelectAllItem);
                if (selectAllItem != null)
                {
                    int count = this.dataSourceNodeList.Count(P => P.IsSelected && P.Title != SelectAllItem);
                    if (!node.IsSelected)
                    {
                        selectAllItem.IsSelected = false;
                    }
                    else if (count == this.dataSourceNodeList.Count - 1)
                    {
                        selectAllItem.IsSelected = true;
                    }
                }
            }

        }


        #endregion

        #region Method

        /// <summary>
        /// Used to display selected item titles when popup closed
        /// </summary>
        /// <returns></returns>
        private string GetSelectedText()
        {
            StringBuilder sb = new StringBuilder();
            foreach (var item in this.dataSourceNodeList)
            {
                if (!item.IsSelected)
                    continue;
                if (item.Title == SelectAllItem)
                    continue;

                sb.Append(item.Title).Append(SeparateString);
            }

            if (sb.Length > 0)
                return sb.ToString().TrimEnd(SeparateString.ToCharArray());
            else
                return null;
        }

        /// <summary>
        /// Use to generate new display items when search in text box
        /// </summary>
        /// <param name="inputText"></param>
        private void FilterDataSourceByInputText(string inputText)
        {
            this.NodeList.Clear();
            ObservableCollection<ComboBoxNode> tempSource = new ObservableCollection<ComboBoxNode>();
            if (!string.IsNullOrEmpty(inputText))
            {
                this.NodeList = this.dataSourceNodeList.FindAll(
                    p => p.Title.StartsWith(inputText.Trim(), true, CultureInfo.CurrentCulture)).ToObservableCollection();
            }
            else
            {
                this.NodeList = this.dataSourceNodeList.ToObservableCollection();
            }
        }

        private void InitDataSourceToComboBoxNodeList()
        {
            dataSourceNodeList.Clear();
            NodeList.Clear();
            TotalCount = 0;
            if (this.ItemsSource != null)
            {
                ComboBoxNode selectAllNode = new ComboBoxNode(SelectAllItem);
                dataSourceNodeList.Add(selectAllNode);
            }

            foreach (var item in this.ItemsSource)
            {
                string title = item.GetType().GetProperty(this.DisplayMemberPath).GetValue(item, null).ToString();
                bool isEnabled = true;
                if (!string.IsNullOrWhiteSpace(this.ItemEnabledPath))
                {
                    try
                    {
                        isEnabled = (bool)item.GetType().GetProperty(this.ItemEnabledPath).GetValue(item, null);
                    }
                    catch { }
                }
                ComboBoxNode node = new ComboBoxNode(title, item);
                node.IsEnabled = isEnabled;
                ChangeNodeIsSelectedStatus(node);
                dataSourceNodeList.Add(node);
                NodeList = dataSourceNodeList.ToObservableCollection();
            }
            //set total count when itemsource changed
            TotalCount = dataSourceNodeList.Count;
        }


        private void ChangeNodeIsSelectedStatus()
        {
            if (this.dataSourceNodeList != null && this.SelectedItems != null)
            {
                int selectedCount = this.SelectedItems.Count;
                foreach (var node in this.dataSourceNodeList)
                {
                    ChangeNodeIsSelectedStatus(node);
                }
            }

            this.DisplayText = GetSelectedText();
        }

        private void ChangeNodeIsSelectedStatus(ComboBoxNode node)
        {
            if (node != null && this.SelectedItems != null)
            {
                int selectedCount = this.SelectedItems.Count;
                if (node.Title == SelectAllItem)
                {
                    if (selectedCount == TotalCount - 1)
                        node.IsSelected = true;
                    else
                        node.IsSelected = false;
                    return;
                }
                if (this.SelectedItems.Contains(node.Item))
                    node.IsSelected = true;
                else
                    node.IsSelected = false;
            }
        }



        #endregion
    }
}

<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                    xmlns:local="clr-namespace:Common.Controls.CustomControls"
                    xmlns:Themes="clr-namespace:Microsoft.Windows.Themes;assembly=PresentationFramework.Aero" 
                     xmlns:Attach="clr-namespace:Common.Common"
                    >

    <Style x:Key="MultiComboBoxEditableTextBox" TargetType="{x:Type TextBox}">
        <Setter Property="OverridesDefaultStyle" Value="true"/>
        <Setter Property="AllowDrop" Value="true"/>
        <Setter Property="MinWidth" Value="0"/>
        <Setter Property="MinHeight" Value="0"/>
        <Setter Property="FocusVisualStyle" Value="{x:Null}"/>
        <Setter Property="ScrollViewer.PanningMode" Value="VerticalFirst"/>
        <Setter Property="Stylus.IsFlicksEnabled" Value="False"/>
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type TextBox}">
                    <ScrollViewer x:Name="PART_ContentHost" Background="Transparent" Focusable="false" HorizontalScrollBarVisibility="Hidden" VerticalScrollBarVisibility="Hidden"/>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>
    <Style  TargetType="{x:Type local:CustomMultipleDropDownBox}">
        <Setter Property="FocusVisualStyle">
            <Setter.Value>
                <Style>
                    <Setter Property="Control.Template">
                        <Setter.Value>
                            <ControlTemplate>
                                <Rectangle Margin="4,4,21,4" SnapsToDevicePixels="True" Stroke="{DynamicResource {x:Static SystemColors.ControlTextBrushKey}}" StrokeThickness="1" StrokeDashArray="1 2"/>
                            </ControlTemplate>
                        </Setter.Value>
                    </Setter>
                </Style>
            </Setter.Value>
        </Setter>
        <Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.WindowTextBrushKey}}"/>
        <Setter Property="Background" Value="#ffffff"/>
        <Setter Property="Height" Value="28"></Setter>
        <Setter Property="Margin" Value="0"/>
        <Setter Property="Padding" Value="5,2,5,2"></Setter>
        <Setter Property="Foreground" Value="#0c223a"/>
        <Setter Property="FontFamily" Value="Arial" />
        <Setter Property="BorderThickness" Value="2"/>
        <Setter Property="VerticalContentAlignment" Value="Center" />
        <Setter Property="ScrollViewer.HorizontalScrollBarVisibility" Value="Auto"/>
        <Setter Property="ScrollViewer.VerticalScrollBarVisibility" Value="Auto"/>
        <Setter Property="ScrollViewer.CanContentScroll" Value="True"/>
        <Setter Property="ScrollViewer.PanningMode" Value="Both"/>
        <Setter Property="Stylus.IsFlicksEnabled" Value="False"/>
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type local:CustomMultipleDropDownBox}">
                    <Border x:Name="BD" CornerRadius="5"  Background="{TemplateBinding Background}" BorderBrush="#5d7fad" BorderThickness="1" SnapsToDevicePixels="True" >
                        <Grid x:Name="MainGrid" SnapsToDevicePixels="True" >
                            <Grid.ColumnDefinitions>
                                <ColumnDefinition Width="*" />
                                <ColumnDefinition  Width="20"/>
                            </Grid.ColumnDefinitions>
                            <Popup x:Name="PART_Popup"  AllowsTransparency="True" Grid.ColumnSpan="2" IsOpen="{Binding IsDropDownOpen, RelativeSource={RelativeSource TemplatedParent}}"   PopupAnimation="{DynamicResource {x:Static SystemParameters.ComboBoxPopupAnimationKey}}" Placement="Bottom">
                                <Themes:SystemDropShadowChrome  x:Name="Shdw"  Color="Transparent" MaxHeight="{TemplateBinding MaxDropDownHeight}" MinWidth="{Binding ActualWidth, ElementName=Placement}" >
                                    <Border x:Name="DropDownBorder" Background="#FFFFFF" BorderThickness="1" CornerRadius="5" BorderBrush="#5d7fad" >
                                        <!--<StackPanel Orientation="Vertical">-->
                                        <!--<ListBox  x:Name="MyListBox"  Height="{TemplateBinding DropDownHeight}" Width="{TemplateBinding Width}"    SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"
                                             KeyboardNavigation.DirectionalNavigation="Contained"   >
                                                </ListBox>-->
                                        <ListBox  x:Name="MyListBox" Margin="2"   Width="{Binding Width,Mode=TwoWay,RelativeSource={RelativeSource TemplatedParent}}" 
                                                      ItemsSource="{Binding NodeList,Mode=OneWay,RelativeSource={RelativeSource TemplatedParent},UpdateSourceTrigger=PropertyChanged}"    
                                                 SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"
                                             KeyboardNavigation.DirectionalNavigation="Contained"   Style="{DynamicResource MultiComboBoxListBox}">

                                        </ListBox>
                                        <!--<ListBox  Foreground="#0c223a" FontSize="14" FontFamily="Arial"  Height="{TemplateBinding DropDownHeight}" x:Name="MySelectedListBox"  SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"
                                             KeyboardNavigation.DirectionalNavigation="Contained" DisplayMemberPath="{TemplateBinding DisplayMemberPath}" ItemsSource="{TemplateBinding SelectedItems}" >
                                                </ListBox>-->
                                        <!--</StackPanel>-->
                                    </Border>
                                </Themes:SystemDropShadowChrome>
                            </Popup>
                            <ToggleButton  IsChecked="{Binding IsDropDownOpen, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}" Grid.Column="1"  
                                           Name="ToggleButton" Focusable="True" Command="{Binding ToggleButtonClickCommand, RelativeSource={RelativeSource TemplatedParent}}"  ClickMode="Press" SnapsToDevicePixels="True" Style="{DynamicResource ComboBoxToggleButton2}"/>
                            <TextBox x:Name="DisPlayTextBlock" Padding="2"  BorderBrush="Red"  Text="{TemplateBinding DisplayText}"  VerticalAlignment="Center"    Background="Transparent"  Foreground="{TemplateBinding Foreground}" 
                                     FontSize="{TemplateBinding Foreground}" FontFamily="{TemplateBinding FontFamily}" HorizontalAlignment="Stretch" Style="{StaticResource MultiComboBoxEditableTextBox}">
                            </TextBox>


                        </Grid>
                    </Border>
                    <ControlTemplate.Triggers>
                        <!--<Trigger Property="Validation.HasError" Value="True">
                            <Setter TargetName="BD" Property="BorderBrush" Value="Red"></Setter>
                        </Trigger>-->
                        <Trigger Property="HasDropShadow" SourceName="PART_Popup" Value="True">
                            <Setter Property="Margin" TargetName="Shdw" Value="0,0,5,5"/>
                            <Setter Property="Color" TargetName="Shdw" Value="#71000000"/>
                        </Trigger>
                        <Trigger Property="HasItems" Value="False">
                            <Setter Property="Height" TargetName="DropDownBorder" Value="95"/>
                        </Trigger>
                        <Trigger Property="IsEnabled" Value="False">
                            <Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.GrayTextBrushKey}}"/>
                            <Setter Property="Background" Value="#FFF4F4F4"/>
                        </Trigger>
                        <MultiTrigger>
                            <MultiTrigger.Conditions>
                                <Condition Property="IsGrouping" Value="True"/>
                                <Condition Property="VirtualizingPanel.IsVirtualizingWhenGrouping" Value="False"/>
                            </MultiTrigger.Conditions>
                            <Setter Property="ScrollViewer.CanContentScroll" Value="False"/>
                        </MultiTrigger>
                        <!--<Trigger Property="CanContentScroll" SourceName="DropDownScrollViewer" Value="False">
                            <Setter Property="Canvas.Top" TargetName="OpaqueRect" Value="{Binding VerticalOffset, ElementName=DropDownScrollViewer}"/>
                            <Setter Property="Canvas.Left" TargetName="OpaqueRect" Value="{Binding HorizontalOffset, ElementName=DropDownScrollViewer}"/>
                        </Trigger>-->
                        <Trigger Property="Validation.HasError" Value="True">
                            <Setter Property="ToolTip">
                                <Setter.Value>
                                    <Binding 
                            Path="(Validation.Errors).CurrentItem.ErrorContent"
                            RelativeSource="{x:Static RelativeSource.Self}"
                            />
                                </Setter.Value>
                            </Setter>
                        </Trigger>
                        <Trigger Property="DisplayTextToolTip" Value="True">
                            <Setter Property="ToolTip">
                                <Setter.Value>
                                    <Binding 
                            Path="DisplayText"
                            RelativeSource="{x:Static RelativeSource.Self}"
                            />
                                </Setter.Value>
                            </Setter>
                        </Trigger>
                    </ControlTemplate.Triggers>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
        <Setter Property="Validation.ErrorTemplate">
            <Setter.Value>
                <ControlTemplate>
                    <AdornedElementPlaceholder>
                        <Border BorderBrush="Red" BorderThickness="1" CornerRadius="5" SnapsToDevicePixels="True" />

                    </AdornedElementPlaceholder>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
        <Style.Triggers>
            <Trigger Property="Attach:AttachProperty.IsMandatory" Value="True">
                <Setter Property="Background" Value="LightYellow"/>
            </Trigger>
            <Trigger Property="IsFocused" Value="True" >
                <Setter Property="Button.Effect">
                    <Setter.Value>
                        <DropShadowEffect ShadowDepth="0" BlurRadius="8" Color="#fe1C67C7"></DropShadowEffect>
                    </Setter.Value>
                </Setter>
            </Trigger>
            <Trigger Property="IsMouseOver" Value="True">
                <Setter Property="Button.Effect">
                    <Setter.Value>
                        <DropShadowEffect ShadowDepth="0" BlurRadius="8" Color="#Fe9DBADF"></DropShadowEffect>
                    </Setter.Value>
                </Setter>
            </Trigger>
            <Trigger Property="IsEnabled" Value="False">
                <Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.GrayTextBrushKey}}"/>
                <Setter Property="Background" Value="#FFF4F4F4"/>
            </Trigger>
        </Style.Triggers>
    </Style>
    <Geometry x:Key="DownArrowGeometry">M 0 0 L 3.5 4 L 7 0 Z</Geometry>
    <Style x:Key="ComboBoxToggleButton2" TargetType="{x:Type ToggleButton}">
        <Setter Property="OverridesDefaultStyle" Value="true"/>
        <Setter Property="IsTabStop" Value="false"/>
        <Setter Property="Focusable" Value="false"/>
        <Setter Property="ClickMode" Value="Press"/>
        <Setter Property="Cursor" Value="Hand"/>
        <Setter Property="Background" Value="Transparent"/>
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type ToggleButton}">
                    <Grid>
                        <Grid.ColumnDefinitions>
                            <ColumnDefinition />
                            <ColumnDefinition Width="20" />
                        </Grid.ColumnDefinitions>
                        <Border x:Name="Border" Grid.ColumnSpan="2"  Background="{TemplateBinding Background}"   SnapsToDevicePixels="True" />
                        <Grid Grid.Column="1" Width="{DynamicResource {x:Static SystemParameters.VerticalScrollBarWidthKey}}" Background="{TemplateBinding Background}">
                            <Path x:Name="Arrow" Data="{StaticResource DownArrowGeometry}" Fill="#5d7fad" HorizontalAlignment="Center" Margin="0,1,0,0" VerticalAlignment="Center"/>
                        </Grid>
                    </Grid>

                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>
    <Style x:Key="MultiComboBoxListBox" TargetType="{x:Type ListBox}">
        <Setter Property="BorderThickness" Value="0"></Setter>
        <Setter Property="ItemTemplate">
            <Setter.Value>
                <DataTemplate>
                    <CheckBox Margin="0,2,0,0" IsChecked="{Binding IsSelected,Mode=TwoWay}"
                              IsEnabled="{Binding IsEnabled, Mode=OneWay}" 
                              Command="{Binding CheckBoxSelectCommand,RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type local:CustomMultipleDropDownBox}}}"
                              CommandParameter="{Binding}"
                              Tag="{Binding Mode=OneWay,UpdateSourceTrigger=PropertyChanged}"
                              Content="{Binding Title}" 
                              Width="{Binding DropDownWidth,Mode=OneWay}"></CheckBox>

                </DataTemplate>
            </Setter.Value>
        </Setter>
    </Style>
</ResourceDictionary>