wpf - ContextMenu.PlacementTarget is not getting set, no idea why

Question

<DataTemplate x:Key="_ItemTemplateA">
  <Grid Tag="{Binding Path=DataContext.Command, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type UserControl}}}">
    <Grid.RowDefinitions>
      <RowDefinition Height="Auto"/>
      <RowDefinition Height="Auto" />
    </Grid.RowDefinitions>
    <ContentControl Content="{Binding}" ContentTemplate="{StaticResource ContentTemplateB}" Grid.Row="0" />
    <ContentControl Name="uiContentPresenter" Content="{Binding ContentView}" Grid.Row="1" Height="0" />
    <ContentControl DataContext="{Binding IsContentDisplayed}" DataContextChanged="IsDisplayed_Changed" Visibility="Collapsed" />
    <Grid.ContextMenu>
      <ContextMenu>
        <MenuItem Header="Text" 
              Command="{Binding Path=PlacementTarget.Tag, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type ContextMenu}}}"
              CommandParameter="{Binding}" />
      </ContextMenu>
    </Grid.ContextMenu>
  </Grid>
</DataTemplate>

The above data template is applied to an ItemsControl. The issue is that for the ContextMenu that is specified for the Grid, the PlacementTarget property is never actually getting set to anything so I cannot get to the Tag property of the Grid which is necessary for passing the Command that should execute on the parent UserControl down to the context menu. I've based this approach off of similar examples such as this: http://social.msdn.microsoft.com/Forums/en-US/wpf/thread/0244fbb0-fd5f-4a03-bd7b-978d7cbe1be3/

I've not been able to identify any other good way to pass this command down. This is setup this way because we are using an MVVM approach so the command we have to execute lives in the View Model of the user control this template is applied in. I've tried explicitly setting the PlacementTarget in a few different ways but it still always shows up as not set.

Answer 1

We have the same problem, but it works randomly. A contextmenu inside the controltemplate in a style for a listbox. We have tried to move the contextmenu to different levels inside the template but the same error occurs.

We think it might be connected to the refreshing of our ICollectionView that is the itemssource of the ListBox.

It seems that when the view refreshes the relative source binding inside the contextmenu is being evaluated before the PlacementTarget is being set.

It feels like a bug in either collectionviewsource or the ContextMenu of WPF...