<DllImport("user32.dll", SetLastError:=True)> Private Shared Function _
    GetWindowLong(ByVal hWnd As IntPtr, ByVal nIndex As Integer) As Integer
    End Function
 
    <DllImport("user32.dll")> Private Shared Function SetWindowLong(ByVal _
      hWnd As IntPtr, ByVal nIndex As Integer, ByVal dwNewLong As IntPtr) As _
      Integer
    End Function
 
    Private Const GWL_STYLE = (-16)
    Private Const WS_BORDER = &HC00000
 
    Private Sub start_Load(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles MyBase.Load
 
        ' Fensterstil ändern
        Dim nStyle As Long
        Dim WS_caption As Long
 
        With Form1
            ' aktuellen Fensterstil emitteln
            nStyle = GetWindowLong(.Handle, GWL_STYLE)
 
            ' Titelleiste entfernen
            nStyle = nStyle And Not WS_CAPTION
 
            ' Neuen Fensterstil setzen
            SetWindowLong(Handle, GWL_STYLE, nStyle)
        End With
    End Sub

 Private Const WS_BORDER = &HC00000

Es ist n?tig das Eure Antworten verst?ndlich und nachvollziehbar sind. (Umgebung: Visual Studio Proff.2010, WPF, XAML, Visual Basic 10, Wind.7)