I want to make subclassing of the toolbar control intercepting the WM_NOTIFY
message to knowing on which button the mouse is over, but the member 'idFrom'
of NMHDR structure return always 0.

Function WindowProc(ByVal hw As Long, ByVal uMsg As Long, ByVal wParam As
Long, ByVal lParam As Long) As Long
' The hw parameter is the 'Toolbar.hwnd' property
Select Case uMsg
Case WM_NOTIFY
Dim hdr As NMHDR
CopyMemory hdr, ByVal lParam, Len(hdr)
If hdr.code = TTN_NEEDTEXT Then
id = hdr.idFrom
End If
Case WM_COMMAND
'....
End Select

Why?
Where mistake?

Thank.