How to track a user's idle time in a VB.NET application

Public Class Form1
 
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Application.AddMessageFilter(New MyFilter)
    End Sub
 
    Private Class MyFilter
        Implements IMessageFilter
 
        Private Const WM_LBUTTONDOWN As Integer = &H201
        Private Const WM_LBUTTONUP As Integer = &H202
        Private Const WM_LBUTTONDBLCLK As Integer = &H203
        Private Const WM_RBUTTONDOWN As Integer = &H204
        Private Const WM_RBUTTONUP As Integer = &H205
        Private Const WM_RBUTTONDBLCLK As Integer = &H206
        Private Const WM_MBUTTONDOWN As Integer = &H207
        Private Const WM_MBUTTONUP As Integer = &H208
        Private Const WM_MBUTTONDBLCLK As Integer = &H209
        Private Const WM_MOUSEWHEEL As Integer = &H20A
        Private Const WM_KEYDOWN As Integer = &H100
        Private Const WM_KEYUP As Integer = &H101
        Private Const WM_SYSKEYDOWN As Integer = &H104
        Private Const WM_SYSKEYUP As Integer = &H105
 
        Private IdleTimeInMinutes As Integer = 10
        Private WithEvents tmr As System.Timers.Timer
        Private TargetDateTime As DateTime
 
        Public Sub New()
            TargetDateTime = DateTime.Now.AddMinutes(IdleTimeInMinutes)
            tmr = New System.Timers.Timer
            tmr.Interval = 1000
            tmr.Start()
        End Sub
 
        Public Function PreFilterMessage(ByRef m As System.Windows.Forms.Message) As Boolean Implements System.Windows.Forms.IMessageFilter.PreFilterMessage
            Select Case m.Msg
                Case WM_MOUSEWHEEL, WM_KEYDOWN, WM_KEYUP, WM_SYSKEYDOWN, WM_SYSKEYUP, _
                        WM_LBUTTONDOWN, WM_LBUTTONUP, WM_LBUTTONDBLCLK, _
                        WM_RBUTTONDOWN, WM_RBUTTONUP, WM_RBUTTONDBLCLK, _
                        WM_MBUTTONDOWN, WM_MBUTTONUP, WM_MBUTTONDBLCLK
 
                    TargetDateTime = DateTime.Now.AddMinutes(IdleTimeInMinutes)
            End Select
        End Function
 
        Private Sub tmr_Elapsed(ByVal sender As Object, ByVal e As System.Timers.ElapsedEventArgs) Handles tmr.Elapsed
            If TargetDateTime.Subtract(DateTime.Now).TotalMilliseconds < 0 Then
                tmr.Stop()
                Application.Exit()
            End If
        End Sub
 
    End Class
 
End Class

                                              

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