Subclassing and Hooking with Visual Basic

Name

SendMessageTimeout

Synopsis

Sends the message to the target window and then waits the number of milliseconds specified in the uTimeout parameter:

Public Declare Function SendMessageTimeout Lib "user32" _
         Alias "SendMessageTimeoutA" _
		(ByVal hwnd As Long, ByVal Msg As Long, _
		ByVal wParam As Long, ByVal lParam As Long, _
		ByVal fuFlags As Long, ByVal uTimeout As Long, _
		lpdwResult 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.

Msg

The message to send to the target window.

wParam

The first parameter of the message.

lParam

The second parameter of the message.

fuFlags

Determines how the message is sent. Valid values are as follows:

SMTO_NORMAL (&H0)

Does not block calling thread until function returns

SMTO_BLOCK (&H1)

Blocks calling thread until function returns

SMTO_ABORTIFHUNG (&H2)

Returns if the application is hung

SMTO_NOTIMEOUTIFNOTHUNG (&H10)

(Win2000 only) Does not return from the function if the application is not hung, even though the timeout period might be expired

uTimeout

The timeout value in milliseconds before the function times out and returns.

lpdwResult

The result of processing the message.

Return Value

Returns 0 if the function succeeded, and nonzero if it timed out or failed.