Here is come code to show a popup in wpf, i've nothing in the popup at the moment, just a gradient background and border.

[code:c#]

<Popup Name="popup1" 
   Width="{Binding ElementName=bdrCalendar, Path=ActualWidth, Converter={StaticResource MarginValueConverter}}"
   Height="150"
   Placement="Center"
   PopupAnimation="Scroll"
   AllowsTransparency="True"
   PlacementTarget="{Binding ElementName=bdrCalendar}"
   MouseDown="popup1_MouseDown" >
 <ctrls:PopupContent />
</Popup>

[/code]