DOCUMENT:Q318677  06-MAR-2002  [visualc]
TITLE   :PRB: System Hangs When You Reach Maximum Child Windows in MDI
PRODUCT :Microsoft C Compiler
PROD/VER::4.0a,4.1,4.2,5.0,6.0
OPER/SYS:
KEYWORDS:

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The information in this article applies to:

 - The Microsoft Foundation Classes (MFC) 
 - Microsoft Visual C++, 32-bit Editions, versions 4.0a, 4.1, 4.2, 5.0, 6.0 
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SYMPTOMS
========

When a multiple-document interface (MDI) application runs and creates many child
windows, the following problems may occur:

 - You cannot create any more child windows.

 - The Start button or menu items do not respond.

 - You cannot run other applications.

 - Other applications may be adversely affected.

This problem may occur even when there is adequate physical memory available in
Microsoft Windows NT, Microsoft Windows 2000, or Microsoft Windows XP. This lack
of physical memory occurs when the desktop heap in the WIN32 subsystem is
depleted.

STATUS
======

This behavior is by design.

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

You cannot determine the maximum number of child windows that can be created in
an application because this depends on several factors:

 - How a program is implemented,
 - The environment of the program, such as:

    - Physical factors, such as implemented memory
    - Variable factors, such as the number of applications that are run
      concurrently.

NOTE: You cannot check the usage status of the desktop heap while an application
is running.

You may also notice memory shortage problems when you run an MDI application that
creates many document templates by using the same menu resource. MFC is not
implemented with a function that deletes added document templates. For
additional information about templates that share a menu resource, click the
article number below to view the article in the Microsoft Knowledge Base:

   Q118435 INFO: Sharing Menus Between MDI Child Windows

REFERENCES
==========

For additional information about the desktop heap, click the article numbers
below to view the articles in the Microsoft Knowledge Base:

   Q126962 Increasing the Desktop Application Heap

   Q184802 PRB: User32.dll or Kernel32.dll Fails to Initialize

Additional query words:

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Keywords          :  
Technology        : kbVCsearch kbAudDeveloper kbMFC kbVC410 kbVC420 kbVC500 kbVC600 kbVC32bitSearch kbVC400a kbVC500Search
Version           : :4.0a,4.1,4.2,5.0,6.0
Issue type        : kbprb

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Copyright Microsoft Corporation 2002.