VB.net/WPFでフォルダを見る

Question

フォルダの変更を監視する方法を試してみるのに問題があります。これは私が持っているところまでです：

Class MainWindow 

<PermissionSet(SecurityAction.Demand, Name:="FullTrust")> _ 
Private Sub Window_Loaded(ByVal sender As System.Object, ByVal e As System.Windows.RoutedEventArgs) Handles MyBase.Loaded 
    Dim Path As String = "C:\Temp" 

    ' Create a new FileSystemWatcher and set its properties. 
    Dim watcher As New FileSystemWatcher() 
    watcher.Path = Path 
    ' Watch for changes in LastAccess and LastWrite times, and 
    ' the renaming of files or directories. 
    watcher.NotifyFilter = (NotifyFilters.LastAccess Or NotifyFilters.LastWrite Or NotifyFilters.FileName Or NotifyFilters.DirectoryName) 
    ' Only watch text files. 
    watcher.Filter = "*.txt" 

    ' Add event handlers. 
    AddHandler watcher.Changed, AddressOf OnChanged 
    AddHandler watcher.Created, AddressOf OnChanged 
    AddHandler watcher.Deleted, AddressOf OnChanged 
    AddHandler watcher.Renamed, AddressOf OnRenamed 

    ' Begin watching. 
    watcher.EnableRaisingEvents = True 

End Sub 

' Define the event handlers. 
Private Shared Sub OnChanged(ByVal source As Object, ByVal e As FileSystemEventArgs) 
    ' Specify what is done when a file is changed, created, or deleted. 
    MsgBox("File: " & e.FullPath & " " & e.ChangeType) 
End Sub 

Private Shared Sub OnRenamed(ByVal source As Object, ByVal e As RenamedEventArgs) 
    ' Specify what is done when a file is renamed. 
    MsgBox("File: {0} renamed to {1}", e.OldFullPath, e.FullPath) 
End Sub 
End Class 

問題は、プログラムがエラーコードなしで終了するフォルダに変更が発生したときです。私はいくつかの関連記事を読んだことがあります。スレッドセーフと関係があることは分かっています。しかし、私はこのプログラムを "スレッドセーフ"にする方法は知らなかった。誰か助けてくれますか？ありがとう！

Answer 1

ここではスレッドセーフの問題は発生していません。

MsgBox("File: {0} renamed to {1}", e.OldFullPath, e.FullPath) 

は何で

MsgBox(String.Format("File: {0} renamed to {1}", e.OldFullPath, e.FullPath))