Private Declare Sub ReleaseCapture Lib "User32" ()
 
Private Declare Function SendMessage Lib "User32" _
  Alias "SendMessageA" (ByVal hwnd As Long, _
  ByVal wMsg As Long, ByVal wParam As Long, _
  lParam As Any) As Long
 
Const WM_NCLBUTTONDOWN = &HA1
Const HTCAPTION = 2
 
Private Sub Form_MouseDown(Button As Integer, _
  Shift As Integer, X As Single, Y As Single)
  Dim lResult As Long
  If Button = 1 Then                          'linke Maustaste
    Call ReleaseCapture
    lResult = SendMessage(Me.hwnd, WM_NCLBUTTONDOWN, _
      HTCAPTION, 0&)
  End If
End Sub