Public Class MyOwnTextbox
    Inherits Windows.Forms.TextBox
    Private Const WM_NCHITTEST As Int32 = &H84
    Private Const WM_KEYDOWN As Int32 = &H100
    Private Const WM_KILLFOCUS As Int32 = &H8
    Private _protect As Boolean
    Declare Function SendMessage Lib "user32.dll" Alias "SendMessageA" ( _
                                                                        ByVal _
                                                                        hwnd As _
                                                                        IntPtr, _
                                                                        ByVal _
                                                                        wMsg As _
                                                                        Int32, _
                                                                        ByVal _
                                                                        wParam _
                                                                        As _
                                                                        Int32, _
                                                                        ByRef _
                                                                        lParam _
                                                                        As _
                                                                        Object) _
                                                                        As _
                                                                        Int32</_
                                                                        b>
    Protected Overrides Sub WndProc(ByRef m As System.Windows.Forms.Message)
        Debug.WriteLine(m.ToString)
        If _protect AndAlso (m.Msg = WM_NCHITTEST OrElse m.Msg = WM_KEYDOWN) _
          Then Return
        MyBase.WndProc(m)
    End Sub
    Public Property Protect() As Boolean
        Get
            Return _protect
        End Get
        Set(ByVal Value As Boolean)
            _protect = Value
            If Value Then
                Me.SendMessage(Me.Handle, Me.WM_KILLFOCUS, Nothing, Nothing)
            End If
        End Set
    End Property

Steve