Subclassing and Hooking with Visual Basic

Name

SendMessageCallback

Synopsis

Sends a message to a window and returns immediately:

Public Declare Function SendMessageCallback Lib "user32" _
         Alias "SendMessageCallbackA" _
		(ByVal hwnd As Long, ByVal Msg As Long, _
		ByVal wParam As Long, ByVal lParam As Long, _
		ByVal lpResultCallBack As Long, ByVal dwData As Long) As Long

Parameters

hwnd

The handle of the target window, or HWND_BROADCAST if the message is to be sent to all top-level windows in the system

wMsg

The message to send to the target window

wParam

The first parameter of the message

lParam

The second parameter of the message

lpResultCallBack

The callback function address

dwData

Data to be passed into the callback function

Return Value

The return value is a success or failure (a zero or a nonzero value, respectively). However, this function uses a callback function to retrieve the message-dependent return value.