ComboBox Background & Diff Display

ComboBoxItemTemplateSelector.cs

using System.Windows;
using System.Windows.Controls;
using System.Windows.Media;

namespace WPFTest.Models
{
  /// <summary>
  /// DataTemplateSelector class for displaying a different value in the combobox selection versus the dropdown items.
  /// </summary>
  public class ComboBoxItemTemplateSelector : DataTemplateSelector
  {
    /// <summary>
    /// The DropDown DataTemplate.
    /// </summary>
    public DataTemplate DropDownTemplate { get; set; }

    /// <summary>
    /// The Selected DataTemplate.
    /// </summary>
    public DataTemplate SelectedTemplate { get; set; }

    /// <summary>
    /// Select the template to use for the indicated container.
    /// </summary>
    /// <param name="item">The item.</param>
    /// <param name="container">The dependency object determining the template.</param>
    /// <returns>The correct template for the ComboBoxItem.</returns>
    public override DataTemplate SelectTemplate(object item, DependencyObject container)
    {
      ComboBoxItem comboBoxItem = this.GetVisualParent<ComboBoxItem>(container);

      if (comboBoxItem != null)
      {
        return this.DropDownTemplate;
      }

      return this.SelectedTemplate;
    }

    /// <summary>
    /// Get the visual parent of the indicated object.
    /// </summary>
    /// <typeparam name="T">The desired return type.</typeparam>
    /// <param name="childObject">The child object.</param>
    /// <returns>The child/parent object of type T.</returns>
    public T GetVisualParent<T>(object childObject) where T : Visual
    {
      DependencyObject child = childObject as DependencyObject;

      while (child != null && !(child is T))
      {
        child = VisualTreeHelper.GetParent(child);
      }

      return child as T;
    }
  }
}

Entry.cs

using System;
using Microsoft.Practices.Prism.Mvvm;

namespace WPFTest.Models
{
  public class Entry : BindableBase
  {
    private bool selected;
    private int id;
    private string type;
    private string description;
    private DateTime effective;
    private DateTime lastdate;
    private string lastuser;

    public bool Selected
    {
      get { return this.selected; }
      set { SetProperty(ref this.selected, value); }
    }

    public int ID
    {
      get { return this.id; }
      set { SetProperty(ref this.id, value); }
    }

    public string Type
    {
      get { return this.type; }
      set { SetProperty(ref this.type, value); }
    }

    public string Description
    {
      get { return this.description; }
      set { SetProperty(ref this.description, value); }
    }

    public DateTime EffectiveDate
    {
      get { return this.effective; }
      set { SetProperty(ref this.effective, value); }
    }

    public DateTime LastChangeTime
    {
      get { return this.lastdate; }
      set { SetProperty(ref this.lastdate, value); }
    }

    public string LastChangeUser
    {
      get { return this.lastuser; }
      set { SetProperty(ref this.lastuser, value); }
    }
  }
}

MainWindow.xaml

<Window x:Class="WPFTest.Views.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:wpfTest="clr-namespace:WPFTest.ViewModels"
        xmlns:prism="clr-namespace:Microsoft.Practices.Prism.Mvvm;assembly=Microsoft.Practices.Prism.Mvvm.Desktop"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
        xmlns:local="clr-namespace:WPFTest.Models"
        mc:Ignorable="d" Title="WPF Test" Height="221.256" Width="605"
        d:DataContext="{d:DesignInstance wpfTest:MainWindowViewModel, IsDesignTimeCreatable=True}"
        prism:ViewModelLocator.AutoWireViewModel="True" WindowStartupLocation="CenterScreen">

    <Window.Resources>
        <ResourceDictionary>
            <ResourceDictionary.MergedDictionaries>
                <ResourceDictionary
                    Source="/WPFTest;Component/Resources/Resources.xaml" />
            </ResourceDictionary.MergedDictionaries>
        </ResourceDictionary>
    </Window.Resources>

    <Grid>
        <ListView 
          ItemsSource="{Binding Entries}"
          SelectedValue="{Binding SelectedEntry}"
          HorizontalAlignment="Stretch"
          VerticalAlignment="Stretch"
          ScrollViewer.CanContentScroll="True"
          SelectionMode="Single"
          Margin="10">
            <ListView.View>
                <GridView>
                    <GridViewColumn Width="Auto">
                        <GridViewColumn.CellTemplate>
                            <DataTemplate>
                                <CheckBox 
                      						IsChecked="{Binding Selected}" 
                      						Command="{Binding DataContext.RowSelectedCommand, RelativeSource={RelativeSource AncestorType={x:Type ListBox}}}"
                      						HorizontalAlignment="Center"/>
                            </DataTemplate>
                        </GridViewColumn.CellTemplate>
                        <GridViewColumnHeader>
                            <ComboBox 
                    					ItemsSource="{Binding Options.Items}"
                    					SelectedValue="{Binding Options.SelectedItem}"
                    					ItemTemplateSelector="{DynamicResource itemTemplateSelector}"
                    					HorizontalAlignment="Stretch"
                    					Margin="0,0,0,0"
                    					VerticalAlignment="Stretch"
                    					Width="44" 
                              Height="34"
                    					FontSize="20"
                    					VerticalContentAlignment="Top"
                    					HorizontalContentAlignment="Left">
                                <ComboBox.Resources>
                                    <DataTemplate x:Key="selectedTemplate">
                                        <TextBlock 
                          								x:Name="displayText"
                          								Text="{Binding DataContext.Options.SelectedDisplay, RelativeSource={RelativeSource AncestorType={x:Type ListBox}}}"
                          								FontSize="20"
                          								Height="22"/>
                                    </DataTemplate>
                                    <DataTemplate x:Key="dropDownTemplate">
                                        <TextBlock Text="{Binding}" FontSize="12"/>
                                    </DataTemplate>
                                    <local:ComboBoxItemTemplateSelector
                        							x:Key="itemTemplateSelector"
                        							SelectedTemplate="{StaticResource selectedTemplate}"
                        							DropDownTemplate="{StaticResource dropDownTemplate}"/>
                                </ComboBox.Resources>
                            </ComboBox>
                        </GridViewColumnHeader>
                    </GridViewColumn>
                    <GridViewColumn
                      Width="Auto"
                			DisplayMemberBinding="{Binding Type, Mode=OneWay}"
                			Header="Type"/>
                </GridView>
            </ListView.View>
        </ListView>
    </Grid>
</Window>

MainWindowViewModel.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Input;
using Microsoft.Practices.Prism.Commands;
using Microsoft.Practices.Prism.Mvvm;
using WPFTest.Models;

namespace WPFTest.ViewModels
{
  /// <summary>
  /// View model for the main window view.
  /// </summary>
  public class MainWindowViewModel : BindableBase
  {
    private Entry selectedEntry;
    private List<Entry> entries;
    private SelectOption options;
    private DelegateCommand rowSelectedCommand;

    /// <summary>
    /// Constructor for the view model.
    /// </summary>
    public MainWindowViewModel()
    {
      this.Entries = new List<Entry>()
      {
        new Entry() 
        {
          Description = "My description.", 
          EffectiveDate = DateTime.Now,
          ID = 1,
          LastChangeTime = DateTime.Now,
          LastChangeUser = "Me",
          Selected = false,
          Type = "Mine"
        },

        new Entry() 
        {
          Description = "Your description.", 
          EffectiveDate = new DateTime(2015, 8, 5, 8, 35, 22, 0),
          ID = 12345,
          LastChangeTime = new DateTime(2015, 8, 5, 8, 35, 22, 0),
          LastChangeUser = "You",
          Selected = false,
          Type = "Yours"
        }
      };

      this.Options = new SelectOption();
      this.Options.SelectChanged = () => { this.OptionsChanged(); };
      this.Options.Items = new List<string>() { string.Empty, "All", "None", "Mine", "Yours" };
      this.Options.SelectedItem = "None";
    }

    public Entry SelectedEntry
    {
      get { return this.selectedEntry; }
      set { SetProperty(ref this.selectedEntry, value); }
    }

    public List<Entry> Entries
    {
      get { return this.entries; }
      set { SetProperty(ref this.entries, value); }
    }

    public SelectOption Options
    {
      get { return this.options; }
      set { SetProperty(ref this.options, value); }
    }

    public ICommand RowSelectedCommand
    {
      get
      {
        if (this.rowSelectedCommand == null)
        {
          Func<bool> canExecute = () =>
            {
              return true;
            };

          Action execute = () =>
            {
              this.Options.SelectedItem = string.Empty;
            };

          this.rowSelectedCommand = new DelegateCommand(execute, canExecute);
        }

        return this.rowSelectedCommand;
      }
    }

    private void OptionsChanged()
    {
      if (this.Options.SelectedItem != string.Empty)
      {
        foreach (Entry entry in this.Entries)
        {
          switch (this.Options.SelectedItem)
          {
            case "All":
              entry.Selected = true;
              break;
            case "None":
              entry.Selected = false;
              break;
            case "Mine":
            case "Yours":
              entry.Selected = entry.Type == this.Options.SelectedItem;
              break;
          }
        }
      }

      bool selected = this.Entries.Any(e => e.Selected);
      bool deselected = this.Entries.Any(e => !e.Selected);
      this.Options.UpdateDisplay(selected, deselected);
    }
  }
}

References.txt

Microsoft.CSharp
Microsoft.Practices.Prism.Mvvm              // Package
Microsoft.Practices.Prism.Mvvm.Desktop
Microsoft.Practices.Prism.SharedInterfaces
PresentationCore
PresentationFramework
PresentationFramework.Royale
System
System.Core
System.Data
System.Data.DataSetExtensions
System.Xaml
System.Xml
System.Xml.Linq
WindowBase

Resources.xaml

<!-- Resources/Resources.xaml -->

<ResourceDictionary
  xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
  xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
  xmlns:sys="clr-namespace:System;assembly=mscorlib"
  xmlns:xctk="http://schemas.xceed.com/wpf/xaml/toolkit"
  xmlns:Royale="clr-namespace:Microsoft.Windows.Themes;assembly=PresentationFramework.Royale">
  
  <ControlTemplate x:Key="ComboBoxControlTemplate1" TargetType="{x:Type ComboBox}">
        <Grid x:Name="templateRoot" SnapsToDevicePixels="True">
            <Grid.ColumnDefinitions>
                <ColumnDefinition Width="*"/>
                <ColumnDefinition MinWidth="{DynamicResource {x:Static SystemParameters.VerticalScrollBarWidthKey}}" Width="0"/>
            </Grid.ColumnDefinitions>
            <Popup x:Name="PART_Popup" AllowsTransparency="True" Grid.ColumnSpan="2" IsOpen="{Binding IsDropDownOpen, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}" Margin="1" PopupAnimation="{DynamicResource {x:Static SystemParameters.ComboBoxPopupAnimationKey}}" Placement="Bottom">
                <Royale:SystemDropShadowChrome x:Name="shadow" Color="Transparent" MaxHeight="{TemplateBinding MaxDropDownHeight}" MinWidth="{Binding ActualWidth, ElementName=templateRoot}">
                    <Border x:Name="DropDownBorder" BorderBrush="{DynamicResource {x:Static SystemColors.WindowFrameBrushKey}}" BorderThickness="1" Background="{DynamicResource {x:Static SystemColors.WindowBrushKey}}">
                        <ScrollViewer x:Name="DropDownScrollViewer">
                            <Grid x:Name="grid" RenderOptions.ClearTypeHint="Enabled">
                                <Canvas x:Name="canvas" HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
                                    <Rectangle x:Name="OpaqueRect" Fill="{Binding Background, ElementName=DropDownBorder}" Height="{Binding ActualHeight, ElementName=DropDownBorder}" Width="{Binding ActualWidth, ElementName=DropDownBorder}"/>
                                </Canvas>
                                <ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
                            </Grid>
                        </ScrollViewer>
                    </Border>
                </Royale:SystemDropShadowChrome>
            </Popup>
            <ToggleButton x:Name="toggleButton" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="{TemplateBinding Background}" Grid.ColumnSpan="2" IsChecked="{Binding IsDropDownOpen, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}">
                <ToggleButton.Style>
                    <Style 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="Template">
                            <Setter.Value>
                                <ControlTemplate TargetType="{x:Type ToggleButton}">
                                    <Border x:Name="templateRoot" BorderBrush="#FFACACAC" BorderThickness="{TemplateBinding BorderThickness}" SnapsToDevicePixels="True">
                                        <Border.Background>
                                            
                                        <!--<LinearGradientBrush EndPoint="0,1" StartPoint="0,0">
                                                <GradientStop Color="#FFF0F0F0" Offset="0"/>
                                                <GradientStop Color="#FFE5E5E5" Offset="1"/>
                                            </LinearGradientBrush>-->
                                        
                                            <SolidColorBrush Color="Yellow"/>
                                        </Border.Background>
                                        <Border x:Name="splitBorder" BorderBrush="Transparent" BorderThickness="1" HorizontalAlignment="Right" Margin="0" SnapsToDevicePixels="True" Width="{DynamicResource {x:Static SystemParameters.VerticalScrollBarWidthKey}}">
                                            <Path x:Name="Arrow" Data="F1M0,0L2.667,2.66665 5.3334,0 5.3334,-1.78168 2.6667,0.88501 0,-1.78168 0,0z" Fill="#FF606060" HorizontalAlignment="Center" Margin="0" VerticalAlignment="Center"/>
                                        </Border>
                                    </Border>
                                    <ControlTemplate.Triggers>
                                        <MultiDataTrigger>
                                            <MultiDataTrigger.Conditions>
                                                <Condition Binding="{Binding IsEditable, RelativeSource={RelativeSource FindAncestor, AncestorLevel=1, AncestorType={x:Type ComboBox}}}" Value="true"/>
                                                <Condition Binding="{Binding IsMouseOver, RelativeSource={RelativeSource Self}}" Value="false"/>
                                                <Condition Binding="{Binding IsPressed, RelativeSource={RelativeSource Self}}" Value="false"/>
                                                <Condition Binding="{Binding IsEnabled, RelativeSource={RelativeSource Self}}" Value="true"/>
                                            </MultiDataTrigger.Conditions>
                                            <Setter Property="Background" TargetName="templateRoot" Value="White"/>
                                            <Setter Property="BorderBrush" TargetName="templateRoot" Value="#FFABADB3"/>
                                            <Setter Property="Background" TargetName="splitBorder" Value="Transparent"/>
                                            <Setter Property="BorderBrush" TargetName="splitBorder" Value="Transparent"/>
                                        </MultiDataTrigger>
                                        <Trigger Property="IsMouseOver" Value="True">
                                            <Setter Property="Fill" TargetName="Arrow" Value="Black"/>
                                        </Trigger>
                                        <MultiDataTrigger>
                                            <MultiDataTrigger.Conditions>
                                                <Condition Binding="{Binding IsMouseOver, RelativeSource={RelativeSource Self}}" Value="true"/>
                                                <Condition Binding="{Binding IsEditable, RelativeSource={RelativeSource FindAncestor, AncestorLevel=1, AncestorType={x:Type ComboBox}}}" Value="false"/>
                                            </MultiDataTrigger.Conditions>
                                            <Setter Property="Background" TargetName="templateRoot">
                                                <Setter.Value>
                                                    <LinearGradientBrush EndPoint="0,1" StartPoint="0,0">
                                                        <GradientStop Color="#FFECF4FC" Offset="0"/>
                                                        <GradientStop Color="#FFDCECFC" Offset="1"/>
                                                    </LinearGradientBrush>
                                                </Setter.Value>
                                            </Setter>
                                            <Setter Property="BorderBrush" TargetName="templateRoot" Value="#FF7EB4EA"/>
                                        </MultiDataTrigger>
                                        <MultiDataTrigger>
                                            <MultiDataTrigger.Conditions>
                                                <Condition Binding="{Binding IsMouseOver, RelativeSource={RelativeSource Self}}" Value="true"/>
                                                <Condition Binding="{Binding IsEditable, RelativeSource={RelativeSource FindAncestor, AncestorLevel=1, AncestorType={x:Type ComboBox}}}" Value="true"/>
                                            </MultiDataTrigger.Conditions>
                                            <Setter Property="Background" TargetName="templateRoot" Value="White"/>
                                            <Setter Property="BorderBrush" TargetName="templateRoot" Value="#FF7EB4EA"/>
                                            <Setter Property="Background" TargetName="splitBorder">
                                                <Setter.Value>
                                                    <LinearGradientBrush EndPoint="0,1" StartPoint="0,0">
                                                        <GradientStop Color="#FFEBF4FC" Offset="0"/>
                                                        <GradientStop Color="#FFDCECFC" Offset="1"/>
                                                    </LinearGradientBrush>
                                                </Setter.Value>
                                            </Setter>
                                            <Setter Property="BorderBrush" TargetName="splitBorder" Value="#FF7EB4EA"/>
                                        </MultiDataTrigger>
                                        <Trigger Property="IsPressed" Value="True">
                                            <Setter Property="Fill" TargetName="Arrow" Value="Black"/>
                                        </Trigger>
                                        <MultiDataTrigger>
                                            <MultiDataTrigger.Conditions>
                                                <Condition Binding="{Binding IsPressed, RelativeSource={RelativeSource Self}}" Value="true"/>
                                                <Condition Binding="{Binding IsEditable, RelativeSource={RelativeSource FindAncestor, AncestorLevel=1, AncestorType={x:Type ComboBox}}}" Value="false"/>
                                            </MultiDataTrigger.Conditions>
                                            <Setter Property="Background" TargetName="templateRoot">
                                                <Setter.Value>
                                                    <LinearGradientBrush EndPoint="0,1" StartPoint="0,0">
                                                        <GradientStop Color="#FFDAECFC" Offset="0"/>
                                                        <GradientStop Color="#FFC4E0FC" Offset="1"/>
                                                    </LinearGradientBrush>
                                                </Setter.Value>
                                            </Setter>
                                            <Setter Property="BorderBrush" TargetName="templateRoot" Value="#FF569DE5"/>
                                        </MultiDataTrigger>
                                        <MultiDataTrigger>
                                            <MultiDataTrigger.Conditions>
                                                <Condition Binding="{Binding IsPressed, RelativeSource={RelativeSource Self}}" Value="true"/>
                                                <Condition Binding="{Binding IsEditable, RelativeSource={RelativeSource FindAncestor, AncestorLevel=1, AncestorType={x:Type ComboBox}}}" Value="true"/>
                                            </MultiDataTrigger.Conditions>
                                            <Setter Property="Background" TargetName="templateRoot" Value="White"/>
                                            <Setter Property="BorderBrush" TargetName="templateRoot" Value="#FF569DE5"/>
                                            <Setter Property="Background" TargetName="splitBorder">
                                                <Setter.Value>
                                                    <LinearGradientBrush EndPoint="0,1" StartPoint="0,0">
                                                        <GradientStop Color="#FFDAEBFC" Offset="0"/>
                                                        <GradientStop Color="#FFC4E0FC" Offset="1"/>
                                                    </LinearGradientBrush>
                                                </Setter.Value>
                                            </Setter>
                                            <Setter Property="BorderBrush" TargetName="splitBorder" Value="#FF569DE5"/>
                                        </MultiDataTrigger>
                                        <Trigger Property="IsEnabled" Value="False">
                                            <Setter Property="Fill" TargetName="Arrow" Value="#FFBFBFBF"/>
                                        </Trigger>
                                        <MultiDataTrigger>
                                            <MultiDataTrigger.Conditions>
                                                <Condition Binding="{Binding IsEnabled, RelativeSource={RelativeSource Self}}" Value="false"/>
                                                <Condition Binding="{Binding IsEditable, RelativeSource={RelativeSource FindAncestor, AncestorLevel=1, AncestorType={x:Type ComboBox}}}" Value="false"/>
                                            </MultiDataTrigger.Conditions>
                                            <Setter Property="Background" TargetName="templateRoot" Value="#FFF0F0F0"/>
                                            <Setter Property="BorderBrush" TargetName="templateRoot" Value="#FFD9D9D9"/>
                                        </MultiDataTrigger>
                                        <MultiDataTrigger>
                                            <MultiDataTrigger.Conditions>
                                                <Condition Binding="{Binding IsEnabled, RelativeSource={RelativeSource Self}}" Value="false"/>
                                                <Condition Binding="{Binding IsEditable, RelativeSource={RelativeSource FindAncestor, AncestorLevel=1, AncestorType={x:Type ComboBox}}}" Value="true"/>
                                            </MultiDataTrigger.Conditions>
                                            <Setter Property="Background" TargetName="templateRoot" Value="White"/>
                                            <Setter Property="BorderBrush" TargetName="templateRoot" Value="#FFBFBFBF"/>
                                            <Setter Property="Background" TargetName="splitBorder" Value="Transparent"/>
                                            <Setter Property="BorderBrush" TargetName="splitBorder" Value="Transparent"/>
                                        </MultiDataTrigger>
                                    </ControlTemplate.Triggers>
                                </ControlTemplate>
                            </Setter.Value>
                        </Setter>
                    </Style>
                </ToggleButton.Style>
            </ToggleButton>
            <ContentPresenter x:Name="contentPresenter" ContentTemplate="{TemplateBinding SelectionBoxItemTemplate}" Content="{TemplateBinding SelectionBoxItem}" ContentStringFormat="{TemplateBinding SelectionBoxItemStringFormat}" HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" IsHitTestVisible="False" Margin="{TemplateBinding Padding}" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" VerticalAlignment="{TemplateBinding VerticalContentAlignment}"/>
        </Grid>
        <ControlTemplate.Triggers>
            <Trigger Property="HasDropShadow" SourceName="PART_Popup" Value="True">
                <Setter Property="Margin" TargetName="shadow" Value="0,0,5,5"/>
                <Setter Property="Color" TargetName="shadow" Value="#71000000"/>
            </Trigger>
            <Trigger Property="HasItems" Value="False">
                <Setter Property="Height" TargetName="DropDownBorder" Value="95"/>
            </Trigger>
            <MultiTrigger>
                <MultiTrigger.Conditions>
                    <Condition Property="IsGrouping" Value="True"/>
                    <!--<Condition>
                        <Condition.Value>
                            <sys:Boolean>False</sys:Boolean>
                        </Condition.Value>
                    </Condition>-->
                </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>
        </ControlTemplate.Triggers>
    </ControlTemplate>
    
    <Style
      TargetType="{x:Type ComboBox}">
      <!-- Uncomment the following Setter to change the ComboBox background. -->  
      <!--<Setter Property="Template"
            Value="{StaticResource ComboBoxControlTemplate1}" />-->
    </Style>
  
</ResourceDictionary>

SelectOption.cs

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Linq;

namespace WPFTest.Models
{
  /// <summary>
  /// Class for the CheckBoxColumnHeader ComboBox options.
  /// </summary>
  public class SelectOption : INotifyPropertyChanged
  {
    /// <summary>
    /// The display value options.
    /// </summary>
    private List<SelectOptionDisplay> displays;

    /// <summary>
    /// The selected display value option.
    /// </summary>
    private string selectedDisplay;

    /// <summary>
    /// The drop-down items.
    /// </summary>
    private List<string> items;

    /// <summary>
    /// The selected drop-down item.
    /// </summary>
    private string selectedItem;

    /// <summary>
    /// The SelectOption constructor.
    /// </summary>
    public SelectOption()
    {
      this.displays = new List<SelectOptionDisplay>()
      {
        new SelectOptionDisplay() { Symbol = "\u2611", Value = "All" },
        new SelectOptionDisplay() { Symbol = "\u2610", Value = "None" },
        new SelectOptionDisplay() { Symbol = "\u2612", Value = "Some" },
      };
    }

    /// <summary>
    /// The property changed event handler.
    /// </summary>
    public event PropertyChangedEventHandler PropertyChanged;

    /// <summary>
    /// The drop-down items.
    /// </summary>
    public List<string> Items
    {
      get
      {
        return this.items;
      }

      set
      {
        this.items = value;
        this.OnPropertyChanged("Items");
      }
    }

    /// <summary>
    /// The selected drop-down item.
    /// </summary>
    public string SelectedItem
    {
      get
      {
        return this.selectedItem;
      }

      set
      {
        this.selectedItem = value;
        this.OnPropertyChanged("SelectedItem");
        this.SelectChanged.Invoke();
      }
    }

    /// <summary>
    /// The selected display option symbol.
    /// </summary>
    public string SelectedDisplay
    {
      get
      {
        return this.selectedDisplay;
      }

      set
      {
        this.selectedDisplay = value;
        this.OnPropertyChanged("SelectedDisplay");
      }
    }

    /// <summary>
    /// Action to take on SelectedItem changed event.
    /// </summary>
    public Action SelectChanged { get; set; }

    /// <summary>
    /// Update the anySelected display based on the columns selections.
    /// </summary>
    /// <param name="anySelected">True if any CheckBoxes in the column are checked.</param>
    /// <param name="anyDeselected">True if any CheckBoxes in the column are not checked.</param>
    public void UpdateDisplay(bool anySelected, bool anyDeselected)
    {
      if (anySelected && !anyDeselected)
      {
        this.SelectedDisplay = this.displays.Single(opt => opt.Value == "All").Symbol;
      }
      else if (anySelected && anyDeselected)
      {
        this.SelectedDisplay = this.displays.Single(opt => opt.Value == "Some").Symbol;
      }
      else if (!anySelected && anyDeselected)
      {
        this.SelectedDisplay = this.displays.Single(opt => opt.Value == "None").Symbol;
      }
    }

    /// <summary>
    /// Raise the PropertyChanged event.
    /// </summary>
    /// <param name="propertyName">The name of the changed property.</param>
    protected void OnPropertyChanged(string propertyName)
    {
      if (this.PropertyChanged != null)
      {
        this.PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
      }
    }

    /// <summary>
    /// The display object.
    /// </summary>
    internal class SelectOptionDisplay
    {
      /// <summary>
      /// The display unicode symbol string.
      /// </summary>
      public string Symbol { get; set; }

      /// <summary>
      /// The display value string.
      /// </summary>
      public string Value { get; set; }
    }
  }
}