CallNextHookEx function (winuser.h)

Passes the hook information to the next hook procedure in the current hook chain. A hook procedure can call this function either before or after processing the hook information.

LRESULT CallNextHookEx(
  [in, optional] HHOOK  hhk,
  [in]           int    nCode,
  [in]           WPARAM wParam,
  [in]           LPARAM lParam
);

[in, optional] hhk

Type: HHOOK

This parameter is ignored.

[in] nCode

Type: int

The hook code passed to the current hook procedure. The next hook procedure uses this code to determine how to process the hook information.

[in] wParam

Type: WPARAM

The wParam value passed to the current hook procedure. The meaning of this parameter depends on the type of hook associated with the current hook chain.

[in] lParam

Type: LPARAM

The lParam value passed to the current hook procedure. The meaning of this parameter depends on the type of hook associated with the current hook chain.

Type: LRESULT

This value is returned by the next hook procedure in the chain. The current hook procedure must also return this value. The meaning of the return value depends on the hook type. For more information, see the descriptions of the individual hook procedures.

Hook procedures are installed in chains for particular hook types. CallNextHookEx calls the next hook in the chain.

Calling CallNextHookEx is optional, but it is highly recommended; otherwise, other applications that have installed hooks will not receive hook notifications and may behave incorrectly as a result. You should call CallNextHookEx unless you absolutely need to prevent the notification from being seen by other applications.

Conceptual

Hooks

Reference

SetWindowsHookEx

UnhookWindowsHookEx function