Wrap Panel Virtualization

<UserControl x:Class="MediaAssistant.Controls.MusicMiddlePanel.MusicMiddlePanelView"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
             xmlns:cal="clr-namespace:Microsoft.Practices.Composite.Presentation.Regions;assembly=Microsoft.Practices.Composite.Presentation" 
             xmlns:UserControls="clr-namespace:MefBasic.UserControls;assembly=MefBasic" xmlns:Constants="clr-namespace:MediaAssistant.Constants" xmlns:MediaAssistant="clr-namespace:MediaAssistant" xmlns:Converters="clr-namespace:MediaAssistant.Converters" Background="White">
	<UserControl.Resources>
        <Converters:TitleToLibraryItemConverter x:Key="TitleToLibraryItemConverter" />
		<Converters:LibraryItemWidthConverter x:Key="LibraryItemWidthConverter" />
		<DataTemplate x:Key="LibraryItemTemplate">
            <Button Style="{StaticResource LinkButtonStyle}" 
                    ToolTip="{Binding RelativeSource={RelativeSource Mode=Self}, Path=Content, Converter={StaticResource LibraryItemSearchTooltipConverter}}"
                    Command="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type UserControl}},Path=DataContext.DataSource.SelectLibraryItemCommand}"
                    CommandParameter="{Binding RelativeSource={RelativeSource Mode=Self}, Path=Content}">
                <Button.Content>
                    <MultiBinding Converter="{StaticResource TitleToLibraryItemConverter}">
                        <Binding/>
                        <Binding RelativeSource="{RelativeSource Mode=FindAncestor,AncestorType={x:Type ListBox}}" Path="Tag"/>
                    </MultiBinding>
                </Button.Content>
                <Button.ContentTemplate>
                    <DataTemplate>
                        <TextBlock Width="{Binding RelativeSource={RelativeSource Mode=FindAncestor,AncestorType={x:Type ListBox}}, Path=ActualWidth, Converter={StaticResource LibraryItemWidthConverter}}" 
                                   Text="{Binding RelativeSource={RelativeSource TemplatedParent}, Path=Content.Title}" TextTrimming="CharacterEllipsis"/>
                    </DataTemplate>
                </Button.ContentTemplate>
            </Button>
        </DataTemplate>
    </UserControl.Resources>
	<DockPanel>
        <UserControls:CollapsibleContainer Name="CollapsibleContainer" DockPanel.Dock="Top" Background="LightGray" Direction="BottomToTop"                                        >
            <UserControls:CollapsibleContainer.Child>
                <Grid>
                    <Grid.ColumnDefinitions>
                        <ColumnDefinition MinWidth="150"/>
                        <ColumnDefinition Width="4"/>
                        <ColumnDefinition MinWidth="150"/>
                        <ColumnDefinition Width="4"/>
                        <ColumnDefinition MinWidth="150"/>
                        <ColumnDefinition Width="4"/>
                        <ColumnDefinition MinWidth="150"/>
                    </Grid.ColumnDefinitions>
                    <Grid.RowDefinitions>
                        <RowDefinition Height="200"/>
                    </Grid.RowDefinitions>
                    <Border Grid.Row="0" Grid.Column="0">
                        <DockPanel>
                            <Border DockPanel.Dock="Top" Background="{StaticResource HeaderGradientBackground}">
                                <TextBlock Text="Genres" FontSize="15"/>
                            </Border>
                            <ListBox
                                ItemsSource="{Binding DataSource.CurrentGenres}"
                                Background="{StaticResource BodyBackground}"
                                ItemTemplate="{StaticResource LibraryItemTemplate}"
                                BorderThickness="0" Tag="Genre"/>
                        </DockPanel>
                    </Border>
                    <Border Grid.Row="0" Grid.Column="2">
                        <DockPanel>
                            <Border DockPanel.Dock="Top" Background="{StaticResource HeaderGradientBackground}">
                                <TextBlock Text="Artists" FontSize="15"/>
                            </Border>
                            <ListBox
                                ItemsSource="{Binding DataSource.CurrentArtists}"
                                Background="{StaticResource BodyBackground}"
                                ItemTemplate="{StaticResource LibraryItemTemplate}"
                                BorderThickness="0" Tag="Artist"/>
                        </DockPanel>
                    </Border>
                    <Border Grid.Row="0" Grid.Column="4">
                        <DockPanel>
                            <Border DockPanel.Dock="Top" Background="{StaticResource HeaderGradientBackground}">
                                <TextBlock Text="Composers" FontSize="15"/>
                            </Border>
                            <ListBox
                                ItemsSource="{Binding DataSource.CurrentComposers}"
                                Background="{StaticResource BodyBackground}"
                                ItemTemplate="{StaticResource LibraryItemTemplate}"
                                BorderThickness="0" Tag="Composer"/>
                        </DockPanel>
                    </Border>
                    <Border Grid.Row="0" Grid.Column="6">
                        <DockPanel>
                            <Border DockPanel.Dock="Top" Background="{StaticResource HeaderGradientBackground}">
                                <TextBlock Text="Album" FontSize="15"/>
                            </Border>
                            <ListBox
                                ItemsSource="{Binding DataSource.CurrentAlbums}"
                                Background="{StaticResource BodyBackground}"
                                ItemTemplate="{StaticResource LibraryItemTemplate}"
                                BorderThickness="0" Tag="Album"/>
                        </DockPanel>
                    </Border>
                </Grid>
            </UserControls:CollapsibleContainer.Child>
        </UserControls:CollapsibleContainer>
        <Border DockPanel.Dock="Top" HorizontalAlignment="Stretch" VerticalAlignment="Stretch">
            <ContentControl cal:RegionManager.RegionName="{x:Static Constants:MediaAssistantRegionNames.MusicResultResion}" ></ContentControl>
        </Border>
    </DockPanel>
</UserControl>