Public Class Form1
    Inherits System.Windows.Forms.Form
    Implements IMessageFilter
 
    Public Sub New()
        MyBase.New()
        InitializeComponent()
 
        Application.AddMessageFilter(Me)
    End Sub
 
    Public Function PreFilterMessage(ByRef m As System.Windows.Forms.Message) _
      As Boolean Implements System.Windows.Forms.IMessageFilter.PreFilterMessage
        If m.Msg = &H100 Then
            If m.WParam.ToInt32 = &H9 And m.LParam.ToInt32 = &HF0001 Then
                Debug.WriteLine("Tab Down")
            End If
        ElseIf m.Msg = &H101 Then
            If m.WParam.ToInt32 = &H9 And m.LParam.ToInt32 = &HC00F0001 Then
                Debug.WriteLine("Tab up")
            End If
        End If
    End Function
 
End Class