FlowDocumentReader 中的上下文菜单

ContextMenu in FlowDocumentReader

ContextMenu 适用于 TextBox 和 FlowDocumentScrollViewer。
ContextMenu 在 FlowDocumentReader 中不起作用。
我刚刚获得 FlowDocumentReader 的默认值。
如何在 FlowDocumentReader 中获取 ContextMenu?

 <TextBox Grid.Row="0">
    <TextBox.ContextMenu>
        <ContextMenu>
            <MenuItem Command="Cut"/>
            <MenuItem Command="Copy"/>
            <MenuItem Command="Paste"/>
            <MenuItem Header="NewItem"/>
        </ContextMenu>
    </TextBox.ContextMenu>
    Some text
</TextBox>
<FlowDocumentReader Grid.Row="1">
    <FlowDocumentReader.ContextMenu>
        <ContextMenu>
            <MenuItem Command="Copy"/>
            <MenuItem Command="SelectAll"/>
            <MenuItem Header="NewItem"/>
        </ContextMenu>
    </FlowDocumentReader.ContextMenu>
    <FlowDocument>
        <Paragraph>some text</Paragraph>
    </FlowDocument>
</FlowDocumentReader>
<FlowDocumentScrollViewer Grid.Row="2">
    <FlowDocumentScrollViewer.ContextMenu>
        <ContextMenu>
            <MenuItem Command="Copy"/>
            <MenuItem Command="SelectAll"/>
            <MenuItem Header="New Item"/>
        </ContextMenu>
    </FlowDocumentScrollViewer.ContextMenu>
    <FlowDocument>
        <Paragraph>some text</Paragraph>
    </FlowDocument>
</FlowDocumentScrollViewer>

解决方案是将 ContextMenu 放在 FlowDocument 上

        <FlowDocumentReader Grid.Row="1">
            <FlowDocument>
                <FlowDocument.ContextMenu>
                    <ContextMenu>
                        <MenuItem Command="Copy"/>
                        <MenuItem Command="SelectAll"/>
                        <MenuItem Header="NewItem"/>
                    </ContextMenu>
                </FlowDocument.ContextMenu>
                <Paragraph>some text</Paragraph>
            </FlowDocument>
        </FlowDocumentReader>