Delegate Function DelegateMitRueckgabeString() As String
 
    Public Function TestFunction() As String
        Dim CurString As String = ""
        If Me.InvokeRequired Then
            Dim dd As New DelegateMitRueckgabeString(AddressOf TestFunction)
            Me.Invoke(dd, New Object() {})
        Else
            Try
                'Do something
            Catch ex As Exception
                MsgBox("Fehler")
            End Try
        End If
        Return CurString
    End Function