Why is my Popup showing opposite the Placement property on some machines?

Question

I have a simple WPF Popup that I am showing when the user clicks a Button.

<Button
    x:Name="aButton"
    Content="Up/Down"
    Width="75"
    Height="30"
    Click="aButton_Click"
/>
<Popup
    PlacementTarget="{Binding ElementName=aButton}"
    Placement="Right"
    VerticalOffset="-31"
    StaysOpen="False"
    AllowsTransparency="True"
>
    <StackPanel>
        <Button Width="45" Height="45" Margin="2,0,2,2" Content="+"/>
        <Button Width="45" Height="45" Margin="2,0,2,0" Content="-"/>
    </StackPanel>
</Popup>

What is extremely weird ... is that this code works differently depending on what machine it runs on.

I run this code on my main desktop and everything works just fine ... and as it should. I run it on my PDC09 netbook ... and the Popup shows opposite (on the left instead of the right as I told it to with the Placement property).

Why is this? And what can I do about it?

Answer 1

I couldn't find anything via Google ... but a lucky search in the WPF forum, quickly found this post. Note to self: don't forget to search the WPF forums if Google can't find anything.

The answer is that my PDC09 netbook is a Tablet PC at heart, and apparently, Microsoft thought it was a good idea to show the Popup opposite to the Placement property on a Tablet PC that is configured for right-handed people ... such that the Popup doesn't appear under the user's hand.

The solution is to revert to custom Popup placement ... if you don't want this behavior.

I would love to hear about any other ways around this problem.