Public Class Form1
    Inherits System.Windows.Forms.Form
 
    Private Declare Function LockWorkstation Lib "User32.dll" Alias _
      "LockWorkStation" () As Long
    Private Declare Function SwitchDesktop Lib "user32" (ByVal hDesktop As _
    Long) As Long
    Private Declare Function OpenDesktop Lib "user32.dll" Alias "OpenDesktopA" ( _
    ByVal lpszDesktop As String, ByVal dwFlags As Long, ByVal fInherit As _
    Boolean, ByVal dwDesiredAccess As Long) As Long
    Private Declare Function CloseDesktop Lib "user32.dll" (ByVal hDesktop As _
    Long) As Long
    Private Declare Function SystemParametersInfo Lib "user32.dll" Alias _
    "SystemParametersInfoA" (ByVal uiAction As Long, ByVal uiParam As Long, _
    ByRef pvParam As Long, ByVal fWinIni As Long) As Long
 
    Private Const SPI_GETSCREENSAVERRUNNING As Long = 114&
    Private Const DESKTOP_READOBJECTS As Long = &H1
    Private Const DESKTOP_CREATEWINDOW As Long = &H2
    Private Const DESKTOP_CREATEMENU As Long = &H4
    Private Const DESKTOP_HOOKCONTROL As Long = &H8
    Private Const DESKTOP_JOURNALRECORD As Long = &H10
    Private Const DESKTOP_JOURNALPLAYBACK As Long = &H20
    Private Const DESKTOP_ENUMERATE As Long = &H40
    Private Const DESKTOP_WRITEOBJECTS As Long = &H80
    Private Const DESKTOP_SWITCHDESKTOP As Long = &H100
 
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles MyBase.Load
 
    End Sub
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles cmdStopMonitoring.Click
        Me.Timer1.Enabled = False
    End Sub
    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles cmdJustMonitor.Click
        Me.Timer1.Enabled = False
        Me.Timer1.Interval = 3000
        Me.Timer1.Enabled = True
    End Sub
    Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles cmdLockWorkstation.Click
        LockWorkstation()
        Me.Timer1.Enabled = False
        Me.Timer1.Interval = 3000
        Me.Timer1.Enabled = True
    End Sub
    Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles Timer1.Tick
        Dim p_lngHwnd As Long
        Dim p_lngRtn As Long
        Dim p_lngErr As Long
        Dim p_lngScreenSaver As Long
        Dim p_blnIsScreenSaver As Boolean
        ' ---------------------------------------
        ' W2K+ -- Will determine if screen saver
        '     is running whether or not the
        '     "Password Protected" box is checked
        ' ---------------------------------------
        p_lngRtn = SystemParametersInfo(uiAction:=SPI_GETSCREENSAVERRUNNING, _
          uiParam:=0&, pvParam:=p_lngScreenSaver, fWinIni:=0&)
        If p_lngRtn = 0 Then
            Debug.Print(Err.LastDllError)
        Else
            p_blnIsScreenSaver = CBool(p_lngScreenSaver)
        End If
        ' ------------------------------------------
        ' If screen saver is *not* running, then
        '     check for locked workstation
        ' ------------------------------------------
        If p_blnIsScreenSaver = True Then
            Debug.Print("Screen saver is running on W2K+")
        Else
            p_lngHwnd = OpenDesktop("default", 0, False, DESKTOP_SWITCHDESKTOP)
            If p_lngHwnd = 0 Then
                Label2.Text = ("Error with OpenDesktop: " & Err.LastDllError)
            Else
                p_lngRtn = SwitchDesktop(p_lngHwnd)
                p_lngErr = Err.LastDllError
                If p_lngRtn = 0 Then
                    If p_lngErr = 0 Then
                        Label2.Text = ("Desktop is locked: " & Err.LastDllError)
                    Else
                        Label2.Text = ("Error with SwitchDesktop: " & _
                          Err.LastDllError)
                    End If
                Else
                    Label1.Text = ("Not locked!" & p_lngErr)
                End If
                p_lngHwnd = CloseDesktop(p_lngHwnd)
            End If
        End If
    End Sub
End Class