WPF

public partial class MainWindow : Window
    {
        ItemList il;
        GroupList gl;

        public MainWindow()
        {
            InitializeComponent();
        }
        private void Window_Loaded(object sender, RoutedEventArgs e)
        {
            il = new ItemList();
            ICollectionView cvs = CollectionViewSource.GetDefaultView(il);
            cvs.SortDescriptions.Add(new SortDescription("_type", ListSortDirection.Ascending));
            cvs.SortDescriptions.Add(new SortDescription("_name", ListSortDirection.Ascending));
            cvs.GroupDescriptions.Add(new PropertyGroupDescription("_type"));
            ListBox2.ItemsSource = cvs;

            gl = new GroupList();
            ICollectionView cvt = CollectionViewSource.GetDefaultView(gl);
            ListBox1.ItemsSource = cvt;
        } 
    }

    public class Item
    {
        public string _type { get; set; }
        public string _name { get; set; }
        public Item()
        {
        }
    }
    public class ItemList : ObservableCollection<Item> {
        public ItemList() {
            base.Add(new Item() { _type = "fruit", _name = "apple" });
            base.Add(new Item() { _type = "vegetable", _name = "potato" });
            base.Add(new Item() { _type = "fruit", _name = "banana" });
            base.Add(new Item() { _type = "vegetable", _name = "tomato" });
            base.Add(new Item() { _type = "fruit", _name = "pear" });
            base.Add(new Item() { _type = "vegetable", _name = "salad" });
            base.Add(new Item() { _type = "fruit", _name = "orange" });
            base.Add(new Item() { _type = "vegetable", _name = "onion" }); 
        }
    }

    public class Group
    {
        public string _groupname { get; set; }
        public List<String> _members { get; set; }
        public string _recipe { get; set; }
        public Group()
        {
        }
    }
    public class GroupList : ObservableCollection<Group>
    {
        public GroupList()
        {
            base.Add(new Group() { _groupname = "Group_1", _members = new List<String>() { "apple", "salad" }, _recipe = "Do this and do that" });
            base.Add(new Group() { _groupname = "Group_2", _members = new List<String>() { "banana", "onion" }, _recipe = "Don't do that and do this" });
        }
    }

<Window x:Class="WpfApplication1.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525"
        Loaded="Window_Loaded">
    <Grid>
        <Label Margin="12,0,378,283" Content="Group"></Label>
        <Label Margin="190,0,200,283" Content="Members"></Label>
        <Label Margin="309,0,81,283" Content="Recipe"></Label>
        <TextBox Margin="309,34,12,12" DataContext="{Binding SelectedItem, ElementName=ListBox1}" Text="{Binding Path=_recipe, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"></TextBox>
        <ListBox Margin="12,34,378,12" Name="ListBox1" SelectionMode="Single">
            <ListBox.ItemTemplate>
                <DataTemplate>
                    <TextBlock Text="{Binding _groupname}" />
                </DataTemplate>
            </ListBox.ItemTemplate>
        </ListBox>
        <ListBox Margin="190,34,199,12" Name="ListBox2" SelectionMode="Multiple" SelectedValuePath="_name">
            <ListBox.ItemTemplate>
                <DataTemplate>
                    <TextBlock Text="{Binding _name}" />
                </DataTemplate>
            </ListBox.ItemTemplate>
            <ListBox.GroupStyle>
                <GroupStyle>
                    <GroupStyle.ContainerStyle>
                        <Style TargetType="{x:Type GroupItem}">
                            <Setter Property="Template">
                                <Setter.Value>
                                    <ControlTemplate>
                                        <Expander Header="{Binding Name}" IsExpanded="True">
                                            <ItemsPresenter />
                                        </Expander>
                                    </ControlTemplate>
                                </Setter.Value>
                            </Setter>
                        </Style>
                    </GroupStyle.ContainerStyle>
                </GroupStyle>
            </ListBox.GroupStyle>
        </ListBox>
    </Grid>
</Window>

System.Windows.Controls.DataVisualization.Charting

<chart:Chart
                    Name="PerfChart"
                    Grid.Row="1"
                    HorizontalAlignment="Stretch"
                    Margin="0,0,0,0"
                    Title="Chart Title"
                    VerticalAlignment="Stretch"
                    Height="Auto" Width="Auto"
               >
    <chart:Chart.LegendStyle>
        <Style TargetType="dv:Legend">
            <Setter Property="VerticalAlignment" Value="Top"></Setter>
            <Setter Property="HorizontalAlignment" Value="Center"></Setter>
        </Style>
    </chart:Chart.LegendStyle>

</chart:Chart>

public void LoadLineChartData()
{

    Dictionary<Date,double> cbHist =
        Controller.CostBasisHistory(strDate, endDate, finInstFilter, port);
    List < KeyValuePair<DateTime, double> > cbList = new List<KeyValuePair<DateTime, double>>();
    foreach(Date dt in cbHist.Keys)
    {
        cbList.Add(new KeyValuePair<DateTime, double>(dt.ToDateTime(),cbHist[dt]) );
    }


    Style pointStyle = new Style(typeof(Control));


    LineSeries series1 = new LineSeries();

    series1.DependentValuePath = "Value";
    series1.IndependentValuePath = "Key";
    series1.Title = "Cost Basis";
    series1.DataPointStyle = pointStyle;
    series1.ItemsSource = cbList;


    PerfChart.Series.Clear();
    PerfChart.Series.Add(series1);
}

<pre>public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();


        string path1 = @"d:\\root\\sounds\\";   /*Environment.GetFolderPath(Environment.SpecialFolder.Desktop);*/
        string[] files = Directory.GetFiles(path1, "*.*", SearchOption.AllDirectories);
        string[] dir = Directory.GetDirectories(path1);
        string result;





        foreach (string sFile in files)
        { 
            Button nwbut = new Button();
            result = System.IO.Path.GetFileNameWithoutExtension(sFile);
            nwbut.Content = result;
            nwbut.Height = 30;
            nwbut.Width = 80;
            nwbut.Margin = Margin = new Thickness(5, 5, 5, 5);
            nwbut.Click += (s, e) => { mediaElement2.Source = new Uri(sFile); };
            WrapPanel wp = new WrapPanel();
            wp.Children.Add(nwbut);

            Grid gr = new Grid();
            gr.Children.Add(wp);
            TabItem ti = new TabItem();
            ti.Content = gr;

                foreach  (string header in dir)
                    ti.Header = System.IO.Path.GetFileNameWithoutExtension(header);
                    tc.Items.Add(ti);

        }
   }
}
}

<ComboBox Grid.Row="2" 
            Grid.Column="1"
            ItemsSource="{Binding Source={local:EnumBindingSource {x:Type local:EmployeeStatus}}, 
                                Converter={StaticResource EnumToListConverter}, 
                                ConverterParameter='SoSo;Good'}"/>

<ListBox Grid.Row="1" 
            x:Name="filesBox"
            AllowDrop="True"
            Grid.Column="2"
            BorderBrush="SteelBlue"
            BorderThickness="1"
            VerticalAlignment="Stretch"
            ItemsSource="{Binding Attachments}"
            SelectedItem="{Binding SelectedAttachment}"
            Margin="2"
            Drop="ListBox_Drop">

<pre>
<ListBox.ItemTemplate>
    <DataTemplate>

        <TextBlock FontSize="14">
            <Hyperlink>
                <TextBlock Text="{Binding FileName}"/>
                    <i:Interaction.Triggers>
                        <i:EventTrigger EventName="Click">
                            <i:InvokeCommandAction Command="{Binding ElementName=attachmentView, Path=DataContext.OpenFileCommand}"
                                                    CommandParameter="{Binding }"/>
                            </i:EventTrigger>
                            <i:EventTrigger EventName="ListBox_Drop">
                                <i:InvokeCommandAction Command="{Binding ElementName=attachmentView, Path=DataContext.DragDropCommand}"
                                                        CommandParameter="{Binding }"/>
                            </i:EventTrigger>
                        </i:Interaction.Triggers>
                </Hyperlink>
            </TextBlock>
    </DataTemplate>
</ListBox.ItemTemplate>

static DependencyPropertyKey BehaviorsKey = DependencyProperty.RegisterAttachedReadOnly(
    "PrivateBehaviors", // REMARK: name is different from property to force GetBehaviors() call
    typeof(BehaviorList),
    typeof(Behavior),
    new UIPropertyMetadata(null));

public static DependencyProperty BehaviorsProperty = BehaviorsKey.DependencyProperty;

public static BehaviorList GetBehaviors(DependencyObject target)
{
    var result = (BehaviorList)target.GetValue(BehaviorsProperty);
    if (result == null)
    {
        result = new BehaviorList(target);
        target.SetValue(BehaviorsKey, result);
    }
    return result;
}

<Slider>
    <gx:Behavior.Behaviors>
        <local:DragLayerGroupBehavior/>
    </gx:Behavior.Behaviors>
</Slider>

public class BehaviorList : IList<Behavior>, System.Collections.IList
{
// .....
}

public class DragLayerGroupBehavior : Behavior
{
// .....
}

Error XLS0503,  A value of type 'DragLayerGroupBehavior' cannot be added to a collection or dictionary of type 'BehaviorList'.
Error XDG0048,  The specified value cannot be assigned to the collection. The following type was expected: "Behavior".