Bubbling and Tunneling Events

Question

Hi,

I'm running the following XAML:

<Window x:Class="Controls.Window1"

xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"

xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"

Title="Controls" Height="300" Width="300"

>

<WrapPanel>

<Button x:Name="button"

PreviewMouseLeftButtonDown="PreviewA"

MouseLeftButtonDown="A">

<Grid

PreviewMouseLeftButtonDown="PreviewB"

MouseLeftButtonDown="B">

<WrapPanel>

<Ellipse Fill="Blue" Margin="5" Width="25" Height="25" Stroke="Black" HorizontalAlignment="Center" VerticalAlignment="Center"

PreviewMouseLeftButtonDown="PreviewC"

MouseLeftButtonDown="C"

/>

<TextBlock Margin="5" HorizontalAlignment="Center" VerticalAlignment="Center" FontSize="14" Text="Click Me!"

PreviewMouseLeftButtonDown="PreviewD"

MouseLeftButtonDown="D"

/>

</WrapPanel>

</Grid>

</Button>

</WrapPanel>

</Window>

Each event handler writes  its name using Debug.WriteLine().

The problem is that the Bubble event does not implemented by the Button. How's that?

The output is:

PreviewA

PreviewB

PreviewC

C

B

Where is 'A' ???

Is it possible that Button already implements MouseLeftButtonDown to create the "Click" event instead? I think that it is a BUG!

Tomer

Answer 1

It's not a bug, it is by design.
Check this thread - the explanation from the documentation:
http://forums.microsoft.com/MSDN/ShowPost.aspx?PostID=426800&SiteID=1