Pues aqui te pongo un ejemplo que acabo de terminar...

[code]
Private Declare Sub mouse_event Lib "user32" (ByVal dwFlags As Long, ByVal dx As Long, ByVal dy As Long, ByVal cButtons As Long, ByVal dwExtraInfo As Long)
Const MOUSEEVENTF_LEFTDOWN = &H2
Const MOUSEEVENTF_LEFTUP = &H4
Const MOUSEEVENTF_MIDDLEDOWN = &H20
Const MOUSEEVENTF_MIDDLEUP = &H40
Const MOUSEEVENTF_MOVE = &H1
Const MOUSEEVENTF_ABSOLUTE = &H8000
Const MOUSEEVENTF_RIGHTDOWN = &H8
Const MOUSEEVENTF_RIGHTUP = &H10
Private Sub Form_Load()
L.AddItem "a"
L.AddItem "a"
L.AddItem "a"
L.AddItem "a"
End Sub
Private Sub L_MouseDown(Button As Integer, Shift As Integer, X As Single, Y As Single)
If Button = 2 Then
mouse_event MOUSEEVENTF_LEFTDOWN Or MOUSEEVENTF_LEFTUP, 0&, 0&, cButt, dwEI
End If
End Sub