Private Declare Function GetAsyncKeyState Lib "user32" (ByVal vKey As Long) As _
  Integer
Const VK_TAB = &H9
 
Private Sub Timer1_Timer()
    keystate = GetAsyncKeyState(VK_TAB)
    If (keystate <> 0) Then
        MsgBox "Tab gedrückt"
    End If
End Sub