A Versatile TreeView for WPF

<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                    xmlns:local="clr-namespace:Hardcodet.Wpf.Samples;assembly="
                    xmlns:vm="clr-namespace:Hardcodet.Wpf.Samples.ViewModel;assembly="
                    xmlns:shop="clr-namespace:SampleShop.Products;assembly="
                    xmlns:cm="clr-namespace:System.ComponentModel;assembly=WindowsBase">
 
  
  <!-- a data template for bound ShopCategory instances -->
  <DataTemplate x:Key="CategoryTemplate"
                DataType="{x:Type shop:ShopCategory}">
    <StackPanel x:Name="GroupPanel"
                Orientation="Horizontal"
                Margin="0,2,0,2">
      <Image x:Name="Folder"
             Source="/Images/FolderClosed.png" />
      <TextBlock x:Name="CategoryName"
                 Margin="2,0,0,0"
                 Text="{Binding Path=CategoryName}" /> 
    </StackPanel>

    <DataTemplate.Triggers>
      <DataTrigger Binding="{Binding Path=IsExpanded, RelativeSource={RelativeSource TemplatedParent}}"
                   Value="True">
        <Setter Property="Source"
                TargetName="Folder"
                Value="/Images/FolderOpen.png" />
      </DataTrigger>

      <DataTrigger Binding="{Binding Path=IsSelected, RelativeSource={RelativeSource TemplatedParent}}"
                   Value="True">
        <Setter Property="Foreground"
                TargetName="CategoryName"
                Value="White" />
        <Setter Property="Source"
                TargetName="Folder"
                Value="/Images/FolderSelected.png" />
        <Setter Property="BitmapEffect">
          <Setter.Value>
            <OuterGlowBitmapEffect GlowColor="Black" />
          </Setter.Value>
        </Setter>
      </DataTrigger>
      
      <!-- custom icons for the root nodes -->
      <DataTrigger Binding="{Binding Path=Header.CategoryName, RelativeSource={RelativeSource TemplatedParent}}"
                   Value="Music">
        <Setter Property="Source"
                TargetName="Folder"
                Value="/Images/Music.png" />
      </DataTrigger>
      <DataTrigger Binding="{Binding Path=Header.CategoryName, RelativeSource={RelativeSource TemplatedParent}}"
                   Value="Movies">
        <Setter Property="Source"
                TargetName="Folder"
                Value="/Images/Movie.png" />
      </DataTrigger>
      <DataTrigger Binding="{Binding Path=Header.CategoryName, RelativeSource={RelativeSource TemplatedParent}}"
                   Value="Books">
        <Setter Property="Source"
                TargetName="Folder"
                Value="/Images/Book.png" />
      </DataTrigger>

    </DataTemplate.Triggers>
  </DataTemplate>


  <!-- this is the style that is applied to the tree -->
  <Style x:Key="SimpleFolders"
         TargetType="{x:Type TreeViewItem}">
    <Style.Resources>
      <!-- override default brushes that show bad background colors -->
      <Brush x:Key="{x:Static SystemColors.HighlightBrushKey}">Transparent</Brush>
      <Brush x:Key="{x:Static SystemColors.ControlBrushKey}">Transparent</Brush>
    </Style.Resources>
    <Setter Property="HeaderTemplate"
            Value="{StaticResource CategoryTemplate}" />
    <Style.Triggers>
    </Style.Triggers>
  </Style>
  
  <!-- 
    A default style for treeview controls. This one will automatically
    be applied as the custom tree's 'TreeStyle' property is not set.
  -->
  <Style x:Key="SimpleTreeStyle" TargetType="{x:Type TreeView}">
    <Setter Property="Background">
      <Setter.Value>
        <LinearGradientBrush EndPoint="0,1"
                             StartPoint="0,0">
          <GradientStop Color="#FFF"
                        Offset="0.0" />
          <GradientStop Color="#AAA"
                        Offset="1.0" />
        </LinearGradientBrush>
      </Setter.Value>
    </Setter>
    <Setter Property="BorderThickness"
            Value="4" />
    <Setter Property="BorderBrush"
            Value="#FFA6AAAB" />
  </Style> 
  
    
  <!-- the context menu for the tree -->
  <ContextMenu x:Key="CategoryMenu">
    <MenuItem Header="Add Subcategory"
              Command="New">
      <MenuItem.Icon>
        <Image Source="/Images/Add.png"
               Width="16"
               Height="16" />
      </MenuItem.Icon>
    </MenuItem>

    <MenuItem Header="Remove Category"
              Command="Delete">
      <MenuItem.Icon>
        <Image Source="/Images/Remove.png"
               Width="16"
               Height="16" />
      </MenuItem.Icon>
    </MenuItem>
    
  </ContextMenu>

  
  <!-- sorts categories by names in ascending order -->
  <cm:SortDescriptionCollection x:Key="AscendingNames">
    <cm:SortDescription PropertyName="Header.CategoryName"
                        Direction="Ascending" />
  </cm:SortDescriptionCollection>

  <!-- sorts categories by names in descending order -->
  <cm:SortDescriptionCollection x:Key="DescendingNames">
    <cm:SortDescription PropertyName="Header.CategoryName"
                        Direction="Descending" />
  </cm:SortDescriptionCollection>

  
  
  <!-- default text style -->
  <Style TargetType="TextBlock">
    <Setter Property="TextWrapping"
            Value="Wrap" />
  </Style>

  
  <!-- the background of the main window -->
  <LinearGradientBrush x:Key="WindowBrush"
                       EndPoint="0.5,1"
                       StartPoint="0.5,0">
    <GradientStop Color="#FFFAFAFA"
                  Offset="0.382" />
    <GradientStop Color="#FF405159"
                  Offset="0" />
    <GradientStop Color="#FF2D3539"
                  Offset="1" />
    <GradientStop Color="#FFDBDDDD"
                  Offset="0.592" />
    <GradientStop Color="#FFA6AAAB"
                  Offset="0.803" />
  </LinearGradientBrush>


  <!-- default style for hyperlinks -->
  <Style TargetType="{x:Type Hyperlink}">
    <Setter Property="Foreground"
            Value="#FFA72222" />
    <Setter Property="TextDecorations"
            Value="None" />
    <Setter Property="ToolTip"
            Value="Visit website" />
  </Style>

</ResourceDictionary>