All ON_NOTIFY handlers have the same signature. For other macros, see the documentation for that macro. The convention for any message sent with WM_NOTIFY is for the lParam parameter of the window message to point to a structure that either is, or begins with, an NMHDR structure - the notification code is actually part of this structure. To find out if there's an extended structure sent with a given notification code, check the documentation for that code. In your specific situation you should be matching a TOOLTIPTEXT**W** structure with the TTN_NEEDTEXTW notification. In general you should consider using the versions with no character-encoding-width indicator, TTN_NEEDTEXT and, as documented in the latest MSDN Library, a NMTTDISPINFO structure.
Stability. What an interesting concept. -- Chris Maunder
