WinCancelShutdown
This function cancels a request for an application to shut down.
Syntax
WinCancelShutdown (hmq, fCancelAlways)
Parameters
- hmq (HMQ) - input
- Handle of message queue for current thread.
- fCancelAlways (BOOL) - input
- Cancellation control.
- TRUE
- No WM_QUIT message should be placed on this queue during system shutdown.
- FALSE
- The applications ignore any outstanding WM_QUIT messages already sent to it, but a message should be sent during other system shutdowns.
Returns
- rc (BOOL) - returns
- Success indicator.
- TRUE
- Successful completion
- FALSE
- Error occurred.
Remarks
On a system shutdown, each message queue normally posts a WM_QUIT message. An application can then handle this message in one of the three ways:
- Destroy its message queue using WinDestroyMsgQueue (hmq).
- Call WinCancelShutdown (hmq, TRUE) to prevent the current thread's event queue from receiving the WM_QUIT messages when the system is shut down. This does not stop other threads from receiving this message.
- Call WinCancelShutdown (hmq, FALSE) to remove all pending WM_QUIT messages from the current thread's event queue but allow future WM_QUIT messages to be posted.
Either way, the system can proceed to the next queue.
Example Code
#define INCL_WINMESSAGEMGR /* Or use INCL_WIN, INCL_PM, Also in COMMON section */ #include <os2.h> HMQ hmq; /* Handle of message queue for current thread. */ BOOL fCancelAlways; /* Cancellation control. */ BOOL rc; /* Success indicator. */ rc = WinCancelShutdown(hmq, fCancelAlways);
This example cancels a shutdown request (WM_QUIT message) and specifies that the message queue will not accept any new WM_QUIT messages.
#define INCL_WINMESSAGEMGR /* Window Message Functions */ #include <os2.h> HAB hab, BOOL fSuccess; /* Success indicator */ HMQ hmq; /* Queue handle */ hmq = WinCreateMsgQueue(hab, 0); fSuccess = WinCancelShutdown(hmq, TRUE);