背景
我已经搜索了一天，没有一个好的结果。我基本上试图实现的是以下树视图：
<Grid>
<TreeView>
<TreeViewItem>
<TreeViewItem.Header>
<StackPanel>
<TextBlock Text="Header Content 1"/>
<TextBlock Text="Header Content 2"/>
</StackPanel>
</TreeViewItem.Header>
<StackPanel >
<TextBlock Margin="-19,0,0,0" Text="Expandable Content 1"/>
<TextBlock Margin="-19,0,0,0" Text="Expandable Content 2"/>
</StackPanel>
</TreeViewItem>
<TreeViewItem>
<TreeViewItem.Header>
<StackPanel>
<TextBlock Text="Content Footer"/>
<TextBlock Text="Content Footer"/>
</StackPanel>
</TreeViewItem.Header>
</TreeViewItem>
</TreeView>
</Grid>
树视图的 Itemspresenter 应在两个内容面板（页眉和页脚）之间呈现其内容，除了在上面的代码中需要两个树视图项目，我希望将其作为 1 个（可选）树视图项目。
如果编辑树视图的默认控件模板以尝试在网格的第三行添加文本块，但由于某种原因，它会在树视图项展开时复制此文本块两次：
<Window.Resources>
<SolidColorBrush x:Key="GlyphBrush" Color="#444" />
<Style x:Key="ExpandCollapseToggleStyle" TargetType="ToggleButton">
<Setter Property="Focusable" Value="False"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="ToggleButton">
<Grid Width="15"
Height="13"
Background="Transparent">
<Path x:Name="ExpandPath"
HorizontalAlignment="Left"
VerticalAlignment="Center"
Margin="1,1,1,1"
Fill="{StaticResource GlyphBrush}"
Data="M 4 0 L 8 4 L 4 8 Z"/>
</Grid>
<ControlTemplate.Triggers>
<Trigger Property="IsChecked" Value="True">
<Setter Property="Data" TargetName="ExpandPath" Value="M 0 4 L 8 4 L 4 8 Z"/>
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
<Style x:Key="TreeViewItemFocusVisual">
<Setter Property="Control.Template">
<Setter.Value>
<ControlTemplate>
<Border>
<Rectangle Margin="0,0,0,0"
StrokeThickness="5"
Stroke="Black"
StrokeDashArray="1 2"
Opacity="0"/>
</Border>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
<Style x:Key="{x:Type TreeViewItem}" TargetType="{x:Type TreeViewItem}">
<Setter Property="Background" Value="Transparent"/>
<Setter Property="HorizontalContentAlignment" Value="{Binding Path=HorizontalContentAlignment, RelativeSource={RelativeSource AncestorType={x:Type ItemsControl}}}"/>
<Setter Property="VerticalContentAlignment" Value="{Binding Path=VerticalContentAlignment, RelativeSource={RelativeSource AncestorType={x:Type ItemsControl}}}"/>
<Setter Property="Padding" Value="1,0,0,0"/>
<Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.ControlTextBrushKey}}"/>
<Setter Property="FocusVisualStyle" Value="{StaticResource TreeViewItemFocusVisual}"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type TreeViewItem}">
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition MinWidth="19" Width="Auto"/>
<ColumnDefinition Width="Auto"/>
<ColumnDefinition Width="*"/>
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="Auto"/>
<RowDefinition Height="Auto"/>
<RowDefinition/>
</Grid.RowDefinitions>
<ToggleButton x:Name="Expander"
Style="{StaticResource ExpandCollapseToggleStyle}"
IsChecked="{Binding Path=IsExpanded,
RelativeSource={RelativeSource TemplatedParent}}"
ClickMode="Press"/>
<Border Name="Bd"
Grid.Column="1"
Background="{TemplateBinding Background}"
BorderBrush="{TemplateBinding BorderBrush}"
BorderThickness="{TemplateBinding BorderThickness}"
Padding="{TemplateBinding Padding}">
<ContentPresenter x:Name="PART_Header" ContentSource="Header" HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}"/>
</Border>
<ItemsPresenter x:Name="ItemsHost"
Grid.Row="1"
Grid.Column="1"
Grid.ColumnSpan="2"/>
<TextBlock Grid.Row="2" Grid.Column="1" Text="Footer Text"></TextBlock>
</Grid>
<ControlTemplate.Triggers>
<Trigger Property="IsExpanded" Value="false">
<Setter TargetName="ItemsHost"
Property="Visibility"
Value="Collapsed"/>
</Trigger>
<Trigger Property="HasItems" Value="false">
<Setter TargetName="Expander"
Property="Visibility"
Value="Hidden"/>
</Trigger>
<MultiTrigger>
<MultiTrigger.Conditions>
<Condition Property="HasHeader" Value="false"/>
<Condition Property="Width" Value="Auto"/>
</MultiTrigger.Conditions>
<Setter TargetName="PART_Header" Property="MinWidth" Value="75"/>
</MultiTrigger>
<MultiTrigger>
<MultiTrigger.Conditions>
<Condition Property="HasHeader" Value="false"/>
<Condition Property="Height" Value="Auto"/>
</MultiTrigger.Conditions>
<Setter TargetName="PART_Header" Property="MinHeight" Value="19"/>
</MultiTrigger>
<Trigger Property="IsSelected" Value="true">
<Setter TargetName="Bd" Property="Background" Value="{DynamicResource {x:Static SystemColors.HighlightBrushKey}}"/>
<Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.HighlightTextBrushKey}}"/> </Trigger>
<MultiTrigger>
<MultiTrigger.Conditions>
<Condition Property="IsSelected" Value="true"/>
<Condition Property="IsSelectionActive" Value="false"/>
</MultiTrigger.Conditions>
<Setter TargetName="Bd" Property="Background" Value="{DynamicResource {x:Static SystemColors.ControlBrushKey}}"/>
<Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.ControlTextBrushKey}}"/>
</MultiTrigger>
<Trigger Property="IsEnabled" Value="false">
<Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.GrayTextBrushKey}}"/>
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</Window.Resources>
<Grid>
<TreeView>
<TreeViewItem>
<TreeViewItem.Header>
<StackPanel>
<TextBlock Text="Treeview Item 1"/>
<TextBlock Text="Header Content"/>
</StackPanel>
</TreeViewItem.Header>
<StackPanel >
<TextBlock Margin="-19,0,0,0" Text="Expandable Content 1"/>
<TextBlock Margin="-19,0,0,0" Text="Expandable Content 2"/>
</StackPanel>
</TreeViewItem>
<TreeViewItem>
<TreeViewItem.Header>
<StackPanel>
<TextBlock Text="Treeview Item 2"/>
<TextBlock Text="Header Content"/>
</StackPanel>
</TreeViewItem.Header>
<StackPanel >
<TextBlock Margin="-19,0,0,0" Text="Expandable Content 1"/>
<TextBlock Margin="-19,0,0,0" Text="Expandable Content 2"/>
</StackPanel>
</TreeViewItem>
</TreeView>
</Grid>
在上面的示例中，页脚内容显示了两次，因为它被添加到 Itemspresenter 的底部。
问题
有谁知道如何解决这个问题？或者也许知道实现相同结果的不同方法？
