how the mousemove event was born

Public Class ArgomentiEvento

    Private _posizione As Point
    Private _pulsante As Byte

    Public Property Posizione As Point
        Get
            Return _posizione
        End Get
        Set(value As Point)
            _posizione = value
        End Set
    End Property

    Public Property Pulsante As Byte
        Get
            Return _pulsante
        End Get
        Set(value As Byte)
            _pulsante = value
        End Set
    End Property

    Public Sub New(pos As Point, puls As Byte)

        Posizione = pos
        Pulsante = puls

    End Sub

End Class

Public Class Form1

    Private Delegate Sub delegato(oggetto As Object, argomenti As argomentiEvento)
    Private Event MuoviMouse As delegato
    Private stringa As String
    Private dbBuffer As BufferedGraphics
    Private dbBufferContext As New BufferedGraphicsContext
    Private Const WM_MOUSEMOVE As Long = &H200

    Protected Overrides Sub WndProc(ByRef m As Message)
        MyBase.WndProc(m)

        Select Case m.Msg
            Case WM_MOUSEMOVE
                Dim x As Integer
                Dim y As Integer

                x = m.LParam.ToInt32 And &HFFFF
                y = m.LParam.ToInt32 >> 16

                RaiseEvent MuoviMouse(Me, New ArgomentiEvento(New Point(x, y), m.WParam.ToInt32))

        End Select

    End Sub

    Private Sub Form_MuoviMouse(sender As Object, e As argomentiEvento) Handles Me.muoviMouse

        Dim pulsante As String = ""

        Select Case e.Pulsante
            Case 0
                pulsante = "NESSUNO"
            Case 1
                pulsante = "SINISTRO"
            Case 2
                pulsante = "DESTRO"
        End Select

        stringa = "X = " & e.Posizione.X & "   Y = " & e.Posizione.Y & "   pulsante premuto = " & pulsante

        Dim dimensione As SizeF = Me.CreateGraphics.MeasureString(stringa, New Font("Arial", 20, FontStyle.Bold))
        Dim x As Integer = (Me.Width - dimensione.Width) / 2
        Dim y As Integer = (Me.Height - dimensione.Height) / 2

        dbBuffer.Graphics.Clear(Me.BackColor)
        dbBuffer.Graphics.DrawString(stringa, New Font("Arial", 20, FontStyle.Regular), New SolidBrush(Color.Black), New Point(x, y))
        dbBuffer.Render(Me.CreateGraphics)

    End Sub

    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles Me.Load

        dbBufferContext.MaximumBuffer = Me.Size
        dbBuffer = dbBufferContext.Allocate(Me.CreateGraphics, New Rectangle(New Point(0, 0), Me.Size))
        dbBuffer.Graphics.SmoothingMode = Drawing2D.SmoothingMode.AntiAlias

    End Sub
End Class