Calling Other Forms from a Main Form in Expression Blend 3

I am trying to create a "desktop" form where a toolbar calls other forms (created in separate XAML files). If I use "child window" as the popup, I can make it work, but when I try to use a regular Canvas (non-modal), I get a build error around the "show". What do I have to include to avoid such a reference issue? Is there an example somewhere showing non-modal form access?
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Try using a rectangle in your pop up like below
<Popup Placement="Bottom" PlacementTarget="{Binding ElementName=PopButton}" StaysOpen="False"  
           IsOpen="{Binding ElementName=PopButton, Path=IsChecked, Mode=TwoWay}">
        <Rectangle Height="100" Width="200" Fill="Blue"/>
TrueFocusSolutionsAuthor Commented:
I'm shocked that no one at "Experts Exchange" mentioned that non-modal child forms were not natively supported in Expression Blend. There are third party tools (Infragistics, Telerik), however, that supply the ability to do this, which is ultimately the solution.

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