title: Is there a "Before" Navigated event?
body: <p>Im using WPF with Navigation Service. I need to catch a situation before the next page is navigated. Is thera any event "before" next page is navigated?</p>
  
  <pre><code>Navigate("MyPage1.xaml")
  Navigate("MyPage2.xaml")'now, I need a event which shows me : FromPage("MyPage1.xaml") before navigating to "MyPage2.xaml".
  </code></pre>
  
  <p>code sample</p>
  
  <pre><code>Private Sub Window_Loaded(ByVal sender As System.Object, ByVal e As System.Windows.RoutedEventArgs) Handles MyBase.Loaded
      Application.NavigationService = Me.ContentFrame.NavigationService
  End Sub
  
  Class Application
      ' Application-level events, such as Startup, Exit, and DispatcherUnhandledException
      ' can be handled in this file.
      Public Shared NavigationService As NavigationService
  End Class
  
  
  
  Private Sub ContentFrame_Navigated(ByVal sender As Object, ByVal e As System.Windows.Navigation.NavigationEventArgs) Handles ContentFrame.Navigated
      If Application.cLang Is Nothing Then Call InitializeLanguage()
      'The following Welcome page is never visible because e.Uri is always the NEXT page
      If e.Uri IsNot Nothing AndAlso (e.Uri.ToString.Contains("Pages/PageWelcome.xaml")) Then
          Call UpdateLanguageCombobox()
      End If
  End Sub
  
  
  
  Private Sub ContentFrame_Navigating(ByVal sender As Object, ByVal e As System.Windows.Navigation.NavigatingCancelEventArgs) Handles ContentFrame.Navigating
      Dim Uri As Uri = CType(sender, Frame).Source
      If Application.cLang Is Nothing Then Call InitializeLanguage()
      'The following Welcome page is never visible because e.Uri is always the NEXT page
      If e.Uri IsNot Nothing AndAlso (e.Uri.ToString.Contains("Pages/PageWelcome.xaml")) Then
          'Call UpdateLanguageCombobox()
      End If
  End Sub
  </code></pre>