title: WPF Interaction trigger IsKeyboardFocusWithinChanged doesn't fire
body: <p>Interaction trigger event "IsKeyboardFocusWithinChanged" doesn't fire, I put breakpoint in command but nothing happens. Trigger is inside UserControl. Command works like a charm, but as I said, it is not firing. In code behind with this event everything works. 
  XAML:</p>
  
  <pre><code>&lt;UserControl x:Class="PixiEditor.Views.MenuButton"
           xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
           xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
           xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
           xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
           xmlns:local="clr-namespace:PixiEditor.Views"
           xmlns:vm="clr-namespace:PixiEditor.ViewModels"
           xmlns:helpers="clr-namespace:PixiEditor.Helpers.Behaviours"
           xmlns:i="http://schemas.microsoft.com/expression/2010/interactivity"
           mc:Ignorable="d" 
           d:DesignHeight="330" d:DesignWidth="200" x:Name="menuButton" DataContext="{DynamicResource MenuButtonViewModel}"&gt;
  &lt;UserControl.Resources&gt;
      &lt;vm:MenuButtonViewModel x:Key="MenuButtonViewModel"/&gt;
  &lt;/UserControl.Resources&gt;
  &lt;i:Interaction.Triggers&gt;
      &lt;i:EventTrigger EventName="IsKeyboardFocusWithinChanged"&gt;
          &lt;i:InvokeCommandAction Command="{Binding CloseListViewCommand}"/&gt;
      &lt;/i:EventTrigger&gt;
  &lt;/i:Interaction.Triggers&gt;
  &lt;StackPanel Name="MainStackPanel"&gt;
  
      &lt;Button Content="{Binding ElementName=menuButton,Path=Text}" Style="{StaticResource MenuButton}" HorizontalAlignment="Left" Command="{Binding OpenListViewCommand}"/&gt;
      &lt;ListView Visibility="{Binding ListViewVisibility}" Style="{StaticResource MenuListViewStyle}"&gt;
          &lt;ContentPresenter Content="{Binding Item, ElementName=menuButton}"/&gt;
          &lt;/ListView&gt;
  &lt;/StackPanel&gt;
  </code></pre>
  
  <p></p>
  
  <p>ViewModel</p>
  
  <pre><code>using PixiEditor.Helpers;
  using System;
  using System.Collections.Generic;
  using System.Linq;
  using System.Text;
  using System.Threading.Tasks;
  using System.Windows;
  
  namespace PixiEditor.ViewModels
  {
  class MenuButtonViewModel : ViewModelBase
  {
      public RelayCommand OpenListViewCommand { get; set; }
      public RelayCommand CloseListViewCommand { get; set; }
      private Visibility _listViewVisibility;
  
      public Visibility ListViewVisibility
      {
          get { return _listViewVisibility; }
          set { _listViewVisibility = value; RaisePropertyChanged("ListViewVisibility"); }
      }
  
  
      public MenuButtonViewModel()
      {
          OpenListViewCommand = new RelayCommand(OpenListView);
          CloseListViewCommand = new RelayCommand(CloseListView);
          ListViewVisibility = Visibility.Hidden;
      }
  
      private void OpenListView(object parameter)
      {
          ListViewVisibility = (ListViewVisibility == Visibility.Hidden) ? Visibility.Visible : Visibility.Hidden;
      }
  
      private void CloseListView(object parameter)
      {
          ListViewVisibility = Visibility.Hidden;
      }
  }
  </code></pre>
  
  <p>}</p>