What can cause PreviewMouseWheel to not tunnel over the margins of a great-grandchild UI element?

I will show you a demo to invoke the PreviewMouseWheel in the UserControl:
The code for UserControl1.xaml:

<UserControl x:Class="InvokePreviewMouseWheel.UserControl1"  
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"  
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"  
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"   
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008"   
             xmlns:local="clr-namespace:InvokePreviewMouseWheel"  
             mc:Ignorable="d"   
             d:DesignHeight="450" d:DesignWidth="800"  
             Name="myUserControl"  
             PreviewMouseWheel="myPreviewMouseWheel"  
             >  

    <Grid>  
        <Border CornerRadius="15" Margin="5,5,5,5" BorderThickness="2" Background="Azure" >  
            <TabControl Name="myTabControl" PreviewMouseWheel="myPreviewMouseWheel">  
                <TabItem Name="myTabItem" PreviewMouseWheel="myPreviewMouseWheel">  
                    <TabItem.Header>  
                        <StackPanel Orientation="Horizontal">  
                            <Ellipse Width="10" Height="10" Fill="DarkGray"/>  
                            <TextBlock>Tab 1</TextBlock>  
                        </StackPanel>  
                    </TabItem.Header>  
                    <StackPanel Name="myStackPanel" PreviewMouseWheel="myPreviewMouseWheel">  
                        <ScrollViewer Name="myScrollViewer" HorizontalScrollBarVisibility="Auto" Height="200" PreviewMouseWheel="myPreviewMouseWheel">  
                            <StackPanel>  
                                <ListBox x:Name="listBox" Height="250" Width="300" FontFamily="15" PreviewMouseWheel="myPreviewMouseWheel"></ListBox>  
                            </StackPanel>  

                        </ScrollViewer>  
                    </StackPanel>  
                </TabItem>  
                <TabItem Header="Tab 2">  
                    <TextBlock Text="{Binding ElementName=textBox1, Path=Text}"/>  
                </TabItem>  
            </TabControl>  
        </Border>    
    </Grid>  
</UserControl>  

The code for UserControl1.xaml.cs:

 private void myPreviewMouseWheel(object sender, MouseWheelEventArgs e)  
        {  
            string message = "PreviewMouseWheelEvent_Element：" + (sender as FrameworkElement).Name.ToString();  
            this.listBox.Items.Add(message);           
        }  

Then input the UserControl1 in the MainWindow.xaml : <local:UserControl1></local:UserControl1>

Build and run the project and you will get the below result: