Hi Bob,

Thanks for your quick reply.

Here is a simple example that is supposed to display a standard Msgbox
whenever the user hovers the mouse over cell A1.

The code seems correct to me but it just doesn't work. In fact it crashes
the whole application !

Code goes into a Standard module:


Declare Function FindWindowEx Lib "user32" Alias "FindWindowExA" _
(ByVal hWnd1 As Long, ByVal hWnd2 As Long, ByVal lpsz1 As String, ByVal
lpsz2 As String) 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

Declare Function GetCursorPos Lib "user32" (lpPoint As POINTAPI) As Long

Type POINTAPI
x As Long
y As Long
End Type

Const GWL_WNDPROC As Long = (-4)
Const WM_MOUSEMOVE = &H200

Dim OldWindowProc As Long
Dim hwnd As Long
Dim lngCurPos As POINTAPI
Dim R As Range

Sub SubClass()

'Subclass The ONLY loaded workbook Window
hwnd = Application.hwnd
hwnd = FindWindowEx(hwnd, 0, "XLDESK", vbNullString)
hwnd = FindWindowEx(hwnd, 0, "EXCEL7", vbNullString)

OldWindowProc = SetWindowLong(hwnd, GWL_WNDPROC, AddressOf NewWindowProc)

End Sub

Function NewWindowProc(ByVal hwnd As Long, ByVal Msg _
As Long, ByVal wParam As Long, ByVal lParam As Long) As _
Long

Set R = ActiveWindow.RangeFromPoint(lngCurPos.x, lngCurPos.y)

If Msg = WM_MOUSEMOVE And R.Address = Range("a1").Address Then
MsgBox "The Mouse is over cell 'A1'", vbInformation
End If
' Pass Intercepted Messages To The Original WinProc
NewWindowProc = CallWindowProc(OldWindowProc, hwnd, Msg, wParam,
lParam)
End Function


Sub UnSubclass()
'UnSubclass The WB window
SetWindowLong hwnd, GWL_WNDPROC, OldWindowProc
End Sub


Caution!! : Before running this code make sure you have saved all your
work as it will crash the Excel application!!!!!!


Unless I am missing something obvious, If anyone out there in the Excel
community can make this simple subclassing example work , I will be amazed !!


Jaafar.
Regards.





"Bob Phillips" wrote:

It works. Show the code.