WPF-嵌套控件 按键事件顺序

<Window x:Class="EventOrderDemo.MainWindow"        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"        Title="MainWindow" Height="350" Width="525">    <DockPanel LastChildFill="True" PreviewKeyDown="Grid_PreviewKeyDown_1" PreviewKeyUp="Grid_PreviewKeyUp_1" KeyDown="Grid_KeyDown_1" KeyUp="Grid_KeyUp_1">        <ListBox DockPanel.Dock="Right" Width="100">            <ListBoxItem>                <TextBox Margin="10,10,10,10">                  </TextBox>            </ListBoxItem>            <ListBoxItem>                <TextBox>                </TextBox>            </ListBoxItem>        </ListBox>        <TextBox  PreviewKeyDown="TextBlock_PreviewKeyDown_1" PreviewKeyUp="TextBlock_PreviewKeyUp_1" KeyDown="TextBlock_KeyDown_1" KeyUp="TextBlock_KeyUp_1" >        </TextBox>    </DockPanel></Window>

Grid_PreviewKeyDown_1
TextBlock_PreviewKeyDown_1
TextBlock_KeyDown_1
Grid_KeyDown_1
Grid_PreviewKeyUp_1
TextBlock_PreviewKeyUp_1
TextBlock_KeyUp_1
Grid_KeyUp_1

Grid_PreviewKeyDown_1里设置e.Handled = true后变为下面

Grid_PreviewKeyDown_1
Grid_PreviewKeyUp_1
TextBlock_PreviewKeyUp_1
TextBlock_KeyUp_1
Grid_KeyUp_1