Imports System.Runtime.InteropServices

Public Class FormImmobiliser
    Inherits NativeWindow

    Private Structure RECT
        Public Left As Integer
        Public Top As Integer
        Public Right As Integer
        Public Bottom As Integer

        Public Sub New(ByVal r As Rectangle)
            Me.Left = r.Left
            Me.Top = r.Top
            Me.Right = r.Right
            Me.Bottom = r.Bottom
        End Sub
    End Structure

    Private Const WM_MOVING As Integer = &H216
    Private Const [TRUE] As Integer = 1

    Private WithEvents target As Form

    Public Sub New(ByVal target As Form)
        Me.target = target
    End Sub

    Private Sub target_HandleCreated(ByVal sender As Object, _
                                     ByVal e As EventArgs) Handles target.HandleCreated
        Me.AssignHandle(Me.target.Handle)
    End Sub

    Private Sub target_HandleDestroyed(ByVal sender As Object, _
                                       ByVal e As EventArgs) Handles target.HandleDestroyed
        Me.ReleaseHandle()
    End Sub

    Protected Overrides Sub WndProc(ByRef m As Message)
        If m.Msg = WM_MOVING Then
            Marshal.StructureToPtr(New RECT(Me.target.Bounds), _
                                   m.LParam, _
                                   False)
            m.Result = New IntPtr([TRUE])
        End If

        MyBase.WndProc(m)
    End Sub

End Class