我的目标只是让RichTextBox占用TreeView中的整个行宽。下面的XAML将生成一个带有RichTextBox元素的TreeView，但宽度只有1个字符宽。
我在RichTextBox中遇到过有关宽度错误的帖子。由于独立的RichTextBox具有预期的宽度，因此可能已修复这些问题。尽管如此，我仍然尝试创建网格，将Alignments设置为Stretch，并将FlowDocument PageWidth绑定到父级但没有成功。
[新] 我正在添加我的应用程序的描述，以防有些人想提出RTB替代方案。我有一个包含10-1000个RTB节点的TreeView。 TextBox和TextBlock不实用，因为我需要完全格式化和用户编辑。
WPF RichTextBox with no width set
A WPF RichTextBox + Button in a StackPanel => what a mess?
<TreeView>
<RichTextBox>
<FlowDocument>
<Paragraph>
<Run>
Hello
</Run>
</Paragraph>
</FlowDocument>
</RichTextBox>
</TreeView>
谢谢，
答案 0 :(得分：1)
如你所说，这是一个known issue
提供的解决方法是：
<TreeView Name="RTBContainer" >
<RichTextBox Width="{Binding Path=ActualWidth, ElementName=RTBContainer, Mode=OneWay}">
<FlowDocument >
<Paragraph>
<Run>
Hello
</Run>
</Paragraph>
</FlowDocument>
</RichTextBox>
</TreeView>
答案 1 :(得分：0)
您的问题源于TreeViewItem默认模板。 TreeViewItem元素包装放置在TreeView中的任何内容。 TreeViewItem的模板是Grid，包含三列，前两列的宽度设置为Auto，而第三列的宽度设置为*。包含Header内容的元素位于第二列，其内容对齐设置为Left。
我已经为TreeViewItem提取了模板并对其进行了修改，以便标题的内容容器跨越第二列和第三列，并将其内容对齐设置为拉伸。
（这是WPF模板的修改后的克隆，所以它有点长）
<TreeView>
<TreeView.ItemContainerStyle>
<Style TargetType="TreeViewItem">
<!-- set the headers content to stretch -->
<Setter Property="Control.HorizontalContentAlignment" Value="Stretch"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="TreeViewItem" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:s="clr-namespace:System;assembly=mscorlib" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="Auto" MinWidth="19" />
<ColumnDefinition Width="Auto" />
<ColumnDefinition Width="*" />
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="Auto" />
<RowDefinition />
</Grid.RowDefinitions>
<ToggleButton IsChecked="False" ClickMode="Press" Name="Expander">
<ToggleButton.Style>
<Style TargetType="ToggleButton">
<Style.Resources>
<ResourceDictionary />
</Style.Resources>
<Setter Property="UIElement.Focusable">
<Setter.Value>
<s:Boolean>False</s:Boolean>
</Setter.Value>
</Setter>
<Setter Property="FrameworkElement.Width">
<Setter.Value>
<s:Double>16</s:Double>
</Setter.Value>
</Setter>
<Setter Property="FrameworkElement.Height">
<Setter.Value>
<s:Double>16</s:Double>
</Setter.Value>
</Setter>
<Setter Property="Control.Template">
<Setter.Value>
<ControlTemplate TargetType="ToggleButton">
<Border Padding="5,5,5,5" Background="#00FFFFFF" Width="16" Height="16">
<Path Fill="#00FFFFFF" Stroke="#FF989898" Name="ExpandPath">
<Path.Data>
<PathGeometry Figures="M0,0L0,6L6,0z" />
</Path.Data>
<Path.RenderTransform>
<RotateTransform Angle="135" CenterX="3" CenterY="3" />
</Path.RenderTransform>
</Path>
</Border>
<ControlTemplate.Triggers>
<Trigger Property="UIElement.IsMouseOver">
<Setter Property="Shape.Stroke" TargetName="ExpandPath">
<Setter.Value>
<SolidColorBrush>#FF1BBBFA</SolidColorBrush>
</Setter.Value>
</Setter>
<Setter Property="Shape.Fill" TargetName="ExpandPath">
<Setter.Value>
<SolidColorBrush>#00FFFFFF</SolidColorBrush>
</Setter.Value>
</Setter>
<Trigger.Value>
<s:Boolean>True</s:Boolean>
</Trigger.Value>
</Trigger>
<Trigger Property="ToggleButton.IsChecked">
<Setter Property="UIElement.RenderTransform" TargetName="ExpandPath">
<Setter.Value>
<RotateTransform Angle="180" CenterX="3" CenterY="3" />
</Setter.Value>
</Setter>
<Setter Property="Shape.Fill" TargetName="ExpandPath">
<Setter.Value>
<SolidColorBrush>#FF595959</SolidColorBrush>
</Setter.Value>
</Setter>
<Setter Property="Shape.Stroke" TargetName="ExpandPath">
<Setter.Value>
<SolidColorBrush>#FF262626</SolidColorBrush>
</Setter.Value>
</Setter>
<Trigger.Value>
<s:Boolean>True</s:Boolean>
</Trigger.Value>
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</ToggleButton.Style>
</ToggleButton>
<!-- other problem was here set the Borders ColumnSpan to 2 -->
<Border BorderThickness="{TemplateBinding Border.BorderThickness}" Padding="{TemplateBinding Control.Padding}" BorderBrush="{TemplateBinding Border.BorderBrush}" Background="{TemplateBinding Panel.Background}" Name="Bd" SnapsToDevicePixels="True" Grid.Column="1" HorizontalAlignment="Stretch" Grid.ColumnSpan="2" >
<ContentPresenter Content="{TemplateBinding HeaderedContentControl.Header}" ContentTemplate="{TemplateBinding HeaderedContentControl.HeaderTemplate}" ContentStringFormat="{TemplateBinding HeaderedItemsControl.HeaderStringFormat}" ContentSource="Header" Name="PART_Header" HorizontalAlignment="{TemplateBinding Control.HorizontalContentAlignment}" SnapsToDevicePixels="{TemplateBinding UIElement.SnapsToDevicePixels}" />
</Border>
<ItemsPresenter Name="ItemsHost" Grid.Column="1" Grid.Row="1" Grid.ColumnSpan="2" />
</Grid>
<ControlTemplate.Triggers>
<Trigger Property="TreeViewItem.IsExpanded">
<Setter Property="UIElement.Visibility" TargetName="ItemsHost">
<Setter.Value>
<x:Static Member="Visibility.Collapsed" />
</Setter.Value>
</Setter>
<Trigger.Value>
<s:Boolean>False</s:Boolean>
</Trigger.Value>
</Trigger>
<Trigger Property="ItemsControl.HasItems">
<Setter Property="UIElement.Visibility" TargetName="Expander">
<Setter.Value>
<x:Static Member="Visibility.Hidden" />
</Setter.Value>
</Setter>
<Trigger.Value>
<s:Boolean>False</s:Boolean>
</Trigger.Value>
</Trigger>
<Trigger Property="TreeViewItem.IsSelected">
<Setter Property="Panel.Background" TargetName="Bd">
<Setter.Value>
<DynamicResource ResourceKey="{x:Static SystemColors.HighlightBrushKey}" />
</Setter.Value>
</Setter>
<Setter Property="TextElement.Foreground">
<Setter.Value>
<DynamicResource ResourceKey="{x:Static SystemColors.HighlightTextBrushKey}" />
</Setter.Value>
</Setter>
<Trigger.Value>
<s:Boolean>True</s:Boolean>
</Trigger.Value>
</Trigger>
<MultiTrigger>
<MultiTrigger.Conditions>
<Condition Property="TreeViewItem.IsSelected">
<Condition.Value>
<s:Boolean>True</s:Boolean>
</Condition.Value>
</Condition>
<Condition Property="Selector.IsSelectionActive">
<Condition.Value>
<s:Boolean>False</s:Boolean>
</Condition.Value>
</Condition>
</MultiTrigger.Conditions>
<Setter Property="Panel.Background" TargetName="Bd">
<Setter.Value>
<DynamicResource ResourceKey="{x:Static SystemColors.ControlBrushKey}" />
</Setter.Value>
</Setter>
<Setter Property="TextElement.Foreground">
<Setter.Value>
<DynamicResource ResourceKey="{x:Static SystemColors.ControlTextBrushKey}" />
</Setter.Value>
</Setter>
</MultiTrigger>
<Trigger Property="UIElement.IsEnabled">
<Setter Property="TextElement.Foreground">
<Setter.Value>
<DynamicResource ResourceKey="{x:Static SystemColors.GrayTextBrushKey}" />
</Setter.Value>
</Setter>
<Trigger.Value>
<s:Boolean>False</s:Boolean>
</Trigger.Value>
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</TreeView.ItemContainerStyle>
<RichTextBox HorizontalAlignment="Stretch" HorizontalContentAlignment="Stretch">
<FlowDocument>
<Paragraph>
<Run>
Hello
</Run>
</Paragraph>
</FlowDocument>
</RichTextBox>
</TreeView>