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 WM_NOTIFY

The WM_NOTIFY message is sent by a common control to its parent window when an event has occurred or the control requires some information.

    WM_NOTIFY 
        idCtrl = (int) wParam; 
        pnmh = (LPNMHDR) lParam; 

    lResult = SendMessage(          // returns LRESULT in lResult     
        (HWND) hWndControl,         // handle to destination control     
        (UINT) WM_NOTIFY,           // message ID     
        (WPARAM) wParam,            // = (WPARAM) (int) idCtrl;    
        (LPARAM) lParam             // = (LPARAM) (LPNMHDR) pnmh; 
    );

Parameters

• idCtrl
  Identifier of the common control sending the message. This identifier is not guaranteed to be unique. An application should use the hwndFrom or idFrom member of the NMHDR structure (passed as the lParam parameter) to identify the control.
• pnmh
  Pointer to an NMHDR structure that contains the notification code and additional information. For some notification messages, this parameter points to a larger structure that has the NMHDR structure as its first member.

Return Values

The return value is ignored except for notification messages that specify otherwise.

Remarks

If the message handler is in a dialog box procedure, you must use the SetWindowLong function with DWL_MSGRESULT to set a return value.

The standard Microsoft® Windows® controls (edit controls, combo boxes, list boxes, buttons, scroll bars, and static controls) do not send WM_NOTIFY messages. To determine if a common control will send a WM_NOTIFY message and, if it will, which notification codes it will send, see the documentation for the control.

For Windows 2000 and later systems, the WM_NOTIFY message cannot be sent between processes.

Message Information

• Header winuser.h
• Minimum operating systems Windows NT 3.51, Windows 95

Message Handler Prototype

int on_notify(HWND hwnd, int cntrl_id, NMHDR* nmhdr)

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Notebook exported on Monday, 7 July 2008, 18:56:50 PM Eastern Daylight Time