How do I swallow the dropdown behavior inside an Expander.Header?

Question

I would like to prevent an Expander from expanding/collapsing when users click inside the header area. This is basically the same question as Q 1396153, but I'd appreciate a more favorable answer :)

Is there a non-invasive way to do this? I am not sure exactly how to attach behavior to the Expander.Header content to prevent mouseclicks. I'm willing to float in content outside the expander itself via a fixed grid layout, but I'm not keen on the solution. Ideas?

XamlPad sample XAML:

<Page xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:sys="clr-namespace:System;assembly=mscorlib" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" >
    <Expander>
    <Expander.Header><TextBlock>
        When I click this text, 
        I don't want to trigger expansion/collapse! Only when I click the 
        expander button do I want to trigger an expand/collapse!
    </TextBlock></Expander.Header>

    <Grid Background="Red" Height="100" Width="100" >
    </Grid>
    </Expander>
</Page>

Answer 1

You can stop mouse clicks on the text box from being handled by your application.

XAML:

<Expander>
    <Expander.Header>
        <TextBlock MouseDown="TextBlock_MouseDown"> 
            When I click this text,  
            I don't want to trigger expansion/collapse! Only when I click the  
            expander button do I want to trigger an expand/collapse!
                    </TextBlock>
        </Expander.Header>
    <Grid Background="Red" Height="100" Width="100" >
    </Grid>
</Expander>

Code behind:

private void TextBlock_MouseDown(object sender, MouseButtonEventArgs e)
{
    e.Handled = true;
}