VB.NETでスクリーンロックしてスクリーンセーバー起動

Imports System.Runtime.InteropServices

Public Class ScreenLockForm
    <DllImport("user32.dll")> _
    Public Shared Function LockWorkStation() As Long
    End Function

    <DllImport("user32.dll")> _
    Public Shared Function SendMessage(ByVal hWnd As IntPtr, _
          ByVal uMsg As Int32, _
          ByVal wParam As Int32, _
          ByVal lParam As Int32) As Int32
    End Function

    Private Const WM_SYSCOMMAND As Int32 = &H112
    Private Const SC_SCREENSAVE As Int32 = &HF140

    Private Sub Lock_Button_Click(sender As System.Object, e As System.EventArgs) _
        Handles Lock_Button.Click
        LockWorkStation()
        SendMessage(Me.Handle, WM_SYSCOMMAND, SC_SCREENSAVE, 0)
        Close()
    End Sub
End Class