Command binding issue in CustomControl: CanExecute() fires, Execute() does not

Question

I'm binding a button command, in a ControlTemplate, to an Execute() method in a CustomControl. I'm using a RoutedCommand, the CanExecute() fires, but the Execute() never does. When the CustomControl is placed in the main window, the code works as expected. When it is placed in a Usercontrol, I have this issue. I have tried several ways to wire up the buttons Command (RelayCommand etc) but can't seem to figure out what's wrong. Any help is appreciated.

For context, this is a TokenizingTextBox control - an early fork of the Xceed open source version. The button is for deleting the token from the list of tokens.

The complete style of a TokenIten (which contains the button of interest):

    <Style TargetType="{x:Type local:TokenItem}">
      <Setter Property="Background" Value="#F3F7FD" />
      <Setter Property="BorderBrush" Value="#BBD8FB" />
      <Setter Property="BorderThickness" Value="1" />
      <Setter Property="Cursor" Value="Arrow" />
      <Setter Property="Padding" Value="2,1,1,1" />
      <Setter Property="Margin" Value="1,0" />
      <Setter Property="Template">
         <Setter.Value>
            <ControlTemplate TargetType="{x:Type local:TokenItem}">
               <Border Background="{TemplateBinding Background}"
                       BorderBrush="{TemplateBinding BorderBrush}"
                       BorderThickness="{TemplateBinding BorderThickness}"
                       Padding="{TemplateBinding Padding}"
                       CornerRadius="0,0,5,5"
                       Margin="{TemplateBinding Margin}"
                       >
                        <StackPanel Orientation="Horizontal" Margin="1" x:Name="myRoot">
                            <ContentPresenter ContentTemplate="{TemplateBinding ContentTemplate}" />

                            <Button Margin="3,0,0,0" Cursor="Hand" 
                                    Command="{x:Static local:TokenizedTextBoxCommands.Delete}" CommandParameter="{TemplateBinding TokenKey}" 
                                    PresentationTraceSources.TraceLevel="High">
                        <!--<Button.Template>
                           <ControlTemplate TargetType="Button">
                              <ContentPresenter />
                           </ControlTemplate>
                        </Button.Template>-->
                        <Image Source="/Resources/delete8.png" Width="8" Height="8" />
                     </Button>
                  </StackPanel>
               </Border>
            </ControlTemplate>
         </Setter.Value>
      </Setter>
   </Style>    

The static Command:

  public static class TokenizedTextBoxCommands
  {
    private static RoutedCommand _deleteCommand = new RoutedCommand();

    public static RoutedCommand Delete => _deleteCommand;
  }

The Custom Control inherits from ItemsControl. In the non-static constructor, we wire up the static delete command to the DeleteToken method:

public TokenizedTextBox()
{
    CommandBindings.Add(new CommandBinding(TokenizedTextBoxCommands.Delete, DeleteToken, CanDelete));
}

Finally CanDelete which just sets CanExecute to true:

    private void CanDelete(object sender, CanExecuteRoutedEventArgs canExecuteRoutedEventArgs)
    {
        canExecuteRoutedEventArgs.CanExecute = true;
    }

And DeleteToken - functionality omitted, signature is really only important thing here:

    private void DeleteToken(object sender, ExecutedRoutedEventArgs e)
    {
        ...
    }

So, hopefully this is enough information for anyone interested in providing guidance/suggestions. Thanks.

Answer 1

Little interest here so I hired a Mentor through Pluralsight. The bindings were correct, but the CustomControl had a RichTextBox which was capturing the Mouse Click. We fixed the issue using a Behavior targeting the Button's PreviewMouseDown.