An application can examine the contents of the message queue by using the WinPeekMsg or WinQueryQueueStatus function. It is useful to examine the queue if the application starts a lengthy operation that additional user input might affect, or if the application needs to look ahead in the queue to anticipate a response to user input.

An application can use WinPeekMsg to check for specific messages in the message queue. This function is useful for extracting messages for a specific window from the queue. It returns immediately if there is no message in the queue. An application can use WinPeekMsg in a loop without requiring the loop to wait for a message to arrive. The following code fragment checks the queue for WM_CHAR messages:

    HAB hab;
    QMSG qmsg;

    if (WinPeekMsg(hab, &qmsg, (HWND) NULL, WM_CHAR, WM_CHAR, PM_NOREMOVE)){
              .
              . /* Process the message. */
              .
    }

An application also can use the WinQueryQueueStatus function to check for messages in the queue. This function is very fast and returns information about the kinds of messages available in the queue and which messages have been posted recently. Most applications use this function in message loops that need to be as fast as possible.