DOCUMENT:Q68552  06-NOV-1999  [win16sdk]
TITLE   :PRB: Cannot Exit Windows with DLL-Instanced Windows Open
PRODUCT :Microsoft Windows Software Development Kit
PROD/VER:WINDOWS:3.0,3.1
OPER/SYS:
KEYWORDS:

======================================================================
-------------------------------------------------------------------------------
The information in this article applies to:

 - Microsoft Windows Software Development Kit (SDK) versions 3.0, 3.1 
-------------------------------------------------------------------------------

SYMPTOMS
========


When the user closes the Windows Program Manager and chooses the OK button in the
Exit Windows dialog box, Windows does not close.

CAUSE
=====

A window was created in a window class registered by a dynamic-link library
(DLL), and the DLL was unloaded from the system before the window was destroyed.

RESOLUTION
==========

Before the DLL is unloaded from the system, explicitly destroy all windows
created in a window class registered by the DLL.

MORE INFORMATION
================

When a DLL is unloaded from memory, all window classes registered by that DLL
are purged. Any windows that have been created with a DLL- registered window
class become invalid when the window class is purged; however, these windows are
not destroyed.

Sending any message to an invalid window returns zero. When Windows sends a
WM_QUERYENDSESSION message to an invalid window, the window returns zero and
Windows does not shut down. Under the debugging version of Windows, this action
creates Fatal Exit code 0x0007 messages.

This problem does not occur under Windows 3.1. When a DLL is unloaded, before its
window classes are purged, any windows created using a DLL- registered window
class are destroyed. When the debugging version of Windows 3.1 destroys a window
in this manner, it produces one of the following four messages:

 - Module unloaded with windows still subclassed

 - Global class freed with existent class windows!

 - Window class freed with existent class windows!

 - USER: Window not destroyed

Additional query words: 3.00 3.10

======================================================================
Keywords          :  
Technology        : kbAudDeveloper kbWin3xSearch kbSDKSearch kbWinSDKSearch kbWinSDK300 kbWinSDK310
Version           : WINDOWS:3.0,3.1

=============================================================================

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS
PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND.  MICROSOFT DISCLAIMS
ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES
OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.  IN NO
EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR
ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL,
CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF
MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE
POSSIBILITY OF SUCH DAMAGES.  SOME STATES DO NOT ALLOW THE EXCLUSION
OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES
SO THE FOREGOING LIMITATION MAY NOT APPLY.

Copyright Microsoft Corporation 1999.