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WINEVENTPROC function pointer

Used to declare a pointer to an application-defined callback function that the system calls in response to events that are generated by an accessible object.


   DWORD         event,
   HWND          hwnd,
   LONG          idObject,
   LONG          idChild,
   DWORD         dwEventThread,
   DWORD         dwmsEventTime


  • hWinEventHook
    Handle to an event hook instance. This value is returned by SetWinEventHook when the hook function is installed, and it is specific to each instance of the hook function.

  • event
    Specifies the event that occurred. This value is one of the event constants.

  • hwnd
    Handle to the window that generates the event, or NULL if no window is associated with the event; for example, the mouse pointer is not associated with a window.

  • idObject
    Identifies the object that is associated with the event. This is either one of the object identifiers or a custom object ID.

  • idChild
    Identifies whether the event was triggered by an object or a child element of the object. If this value is CHILDID_SELF, the event was triggered by the object; if this value is a child ID, the event was triggered by a child element.

  • dwEventThread
    Identifies the thread that generated the event, or the thread that owns the current window.

  • dwmsEventTime
    Specifies the time, in milliseconds, that the event was generated.

Return value

This function pointer does not return a value.


For more information, see WinEventProc.


Minimum supported client

Windows 2000 Professional [desktop apps only]

Minimum supported server

Windows Server 2003 [desktop apps only]


Active Accessibility 1.3 RDK on Windows NT 4.0 with SP6 and later and Windows 95


Winuser.h (WINVER >= 0x0500) (include Windows.h)