The TTN_NEEDTEXT notification message retrieves text for a tool. This notification message is sent in the form of a WM_NOTIFY message.
TTN_NEEDTEXT idTT = (int) wParam; lpttt = (LPTOOLTIPTEXT) lParam;
No return value.
This notification message is sent to the window specified in the hwnd member of the TOOLINFO structure for the tool. This notification is sent only if the LPSTR_TEXTCALLBACK value is specified when the tool is added to a ToolTip control.
When a TTN_NEEDTEXT notification is received, the application can set or clear the TTF_RTLREADING value in the uFlags member of the TOOLTIPTEXT structure pointed to by lpttt as required. This is the only flag that can be changed during the notification callback.