MouseMove interesting API but one glitch remains...

Ok here's my question since reacting speed was crutial with this one I diceded to use this API to control MouseMove off of a listbox I have.
I love the acuracy and speed of it but the only problem, it will trigger the "mouse leave event" if I hover over the listbox's own vertical scrollbar.
I tried to find a spot within the code where I could tell it to trigger only if it leaves off the scrollbar area on the right of the listbox but I miserably failed!#"!
Anyone see the answer to this problem?
Thanks a bunch

VB Code:

'MODULE-------------------------------------------------------------
Option Explicit
Public Const TME_CANCEL = &H80000000
Public Const TME_HOVER = &H1&
Public Const TME_LEAVE = &H2&
Public Const TME_NONCLIENT = &H10&
Public Const TME_QUERY = &H40000000
Public Const WM_MOUSELEAVE = &H2A3&
 
Public Type TRACKMOUSEEVENTTYPE
    cbSize As Long
    dwFlags As Long
    hwndTrack As Long
    dwHoverTime As Long
 
End Type
 
Public Declare Function TrackMouseEvent Lib "user32" (lpEventTrack As TRACKMOUSEEVENTTYPE) As Long
Public Declare Function SetCursorPos Lib "user32.dll" (ByVal X As Long, ByVal Y As Long) As Long
 
Declare Function SetWindowLong Lib "user32" Alias "SetWindowLongA" (ByVal hWnd As Long, ByVal nIndex As Long, ByVal dwNewLong As Long) As Long
Declare Function CallWindowProc Lib "user32" Alias "CallWindowProcA" (ByVal lpPrevWndFunc As Long, ByVal hWnd As Long, ByVal Msg As Long, ByVal wParam As Long, ByVal lParam As Long) As Long
 
Public Const GWL_WNDPROC = (-4)
Public PrevProc As Long
 
Public Sub HookForm(F As Control)
PrevProc = SetWindowLong(F.hWnd, GWL_WNDPROC, AddressOf WindowProc)
End Sub
 
Public Sub UnHookForm(F As Control)
SetWindowLong F.hWnd, GWL_WNDPROC, PrevProc
End Sub
 
Public Function WindowProc(ByVal hWnd As Long, ByVal uMsg As Long, ByVal wParam As Long, ByVal lParam As Long) As Long
 
If uMsg = WM_MOUSELEAVE Then
    'if we receive a WM_MOUSELEAVE message, show it
    'set caption back to what it was
 Form1.List6.Height = 22
 
End If
 
WindowProc = CallWindowProc(PrevProc, hWnd, uMsg, wParam, lParam)
End Function
 
 
'FORM1-----------------------------------------------------------------------
Private Sub Form_Load()
  HookForm List6
End Sub
 
 
Private Sub List6_MouseMove(Button As Integer, Shift As Integer, X As Single, Y As Single)
Dim ET As TRACKMOUSEEVENTTYPE
 
    'initialize structure
    ET.cbSize = Len(ET)
    ET.hwndTrack = List6.hWnd
    ET.dwFlags = TME_LEAVE
    'start the tracking
    TrackMouseEvent ET
    List6.Height = 150
End Sub
 
Private Sub Form_Unload(Cancel As Integer)
  UnHookForm List6
End Sub

I'm not sure on how fast this will be, but you could, on recieving the WM_MOUSELEAVE message, test over which window you are hovering/moving and see if this window is a child of the listbox.

VB Code:

'To get the window over which you are moving you can use:
Public Declare Function WindowFromPoint Lib "user32" Alias "WindowFromPoint" (ByVal xPoint As Long, ByVal yPoint As Long) As Long
'To get the parent of the window you can use:
Public Declare Function GetParent Lib "user32" Alias "GetParent" (ByVal hwnd As Long) As Long