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The BroadcastSystemMessage function sends a message to the specified recipients. The recipients can be applications, installable drivers, Windows-based network drivers, system-level device drivers, or any combination of these system components.

Declare Function BroadcastSystemMessage Lib "user32" Alias "BroadcastSystemMessage" (ByVal dw As Long, pdw As Long, ByVal un As Long, ByVal wParam As Long, ByVal lParam As Long) As Long

Operating Systems Supported
Requires Windows NT 4.0 or later; Requires Windows 95 or later


Parameter Information
- dwFlags
Option flags. Can be a combination of the following values:
Flush the disk after each recipient processes the message.
Continue to broadcast the message, even if the time-out period elapses or one of the recipients is hung..
Do not send the message to windows that belong to the current task. This prevents an application from receiving its own message.
Force a hung application to time out. If one of the recipients times out, do not continue broadcasting the message.
Wait for a response to the message, as long as the recipient is not hung. Do not time out.
Post the message. Do not use in combination with BSF_QUERY.
Send the message to one recipient at a time, sending to a subsequent recipient only if the current recipient returns TRUE.

- lpdwRecipients
Pointer to a variable that contains and receives information about the recipients of the message. The variable can be a combination of the following values:
Broadcast to all system components.
Windows NT only: Broadcast to all desktops. Requires the SE_TCB_NAME privilege.
Broadcast to applications.
Windows 95: Broadcast to installable drivers.
Windows NT: This value is not meaningful.
Windows 95: Broadcast to Windows-based network drivers.
Windows NT: This value is not meaningful.
Windows 95: Broadcast to all system-level device drivers.
Windows NT: This value is not meaningful.

When the function returns, this variable receives a combination of these values identifying which recipients actually received the message.
If this parameter is NULL, the function broadcasts to all components.

- uiMessage
Identifier of the system message.

- wParam
32-bit message-specific value.

- lParam
32-bit message-specific value.

Return Values
If the function succeeds, the return value is a positive value.

If the function is unable to broadcast the message, the return value is -1.

If the dwFlags parameter is BSF_QUERY and at least one recipient returned BROADCAST_QUERY_DENY to the corresponding message, the return value is zero.

Last update: 07 April 2006