Window Handle from CreateWindow will colse itself when thread exit?

[fitatc]

first, the MSDN about CreateWindow() not mention of close the handle of window it returns. :confused:is it means that we donnot need to care about it?(Sorry about the title if it is true) second, I test of this in the code like this

HWND hWnd;
unsigned __stdcall SecondThreadFunc( void* pArguments )
{
hWnd = CreateWindow(
L"BUTTON"
,L"dmyWnd"
,WS_DISABLED
,CW_USEDEFAULT
,CW_USEDEFAULT
,0
,0
,NULL
,NULL
,::AfxGetInstanceHandle()
,NULL
);
while( (bRet = GetMessage( &msg, NULL, 0, 0 )) != 0)
{
if (bRet == -1)
{
// handle the error and possibly exit
TRACE(L"[Thread] ERROR\n");
}
else
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}
}
return 0;
}

_beginthreadex( NULL, 0, &SecondThreadFunc, NULL, 0, &threadID ); // called by MainThread

I try to call

int nRt = ::GetWindowText(hWnd, cs, 256);

before and after I

::PostThreadMessage(threadID, WM_QUIT, 0, 0);

to end the thread. The result is sccess when thread alive and invalid handle when thread exit. :confused:I am not sure if this can prove that window handle is be safely closed.Could any one tell me that is it true "Window Handle from CreateWindow will colse itself when thread exit"

[Stuart Dootson]

fitatc wrote:

Could any one tell me that is it true "Window Handle from CreateWindow will colse itself when thread exit"

No, not necessarily - it'll be because the thread's has gone. GetWindowText performs a SendMessage of WM_GETTEXT to the window you want. SendMessage to a window owned by another thread means switching to the thread and calling the window's WndProc. If the thread no longer exists, that's not possible, so the function returns an error.

[Stephen Hewitt]

To a certain extent windows (HWNDs) belong to the thread that created them. For example, the thread that created the window is the thread that pumps its messages. See Thread affinity of user interface objects, part 1: Window handles[^] for deatils. It doesn't make sense to create a window with a thread and then let it outlive its parent thread.

Steve

[Lost User]

Hi,

fitatc wrote:

I am not sure if this can prove that window handle is be safely closed.Could any one tell me

User applications do not manage window handles. To be more specific your application does not create/destroy or manage windows directly. The windows kernel does all of this for you when you request it. There is a device driver named 'Win32k.sys' which through ntdll.dll creates and manages the window for you. when you make a call to CreateWindow it ultimately passes through VerNtUserCreateWindowEx then ZwUserCreateWindowEx and your window is created. Event messages are then placed in the message que associated with the window. At this point your application can retrieve these messages and react to them. If you don't understand anything I just said... just remember that you do not need to close window handles. Best Wishes, -David Delaune

[fitatc]

Thank you very much, that just the answer what I need!!! :-D :-D