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Article: Q134283
Product(s): Microsoft C Compiler
Version(s): winnt:
Operating System(s): 
Keyword(s): kbMFC kbToolbar KbUIDesign kbVC200bug kbVC210fix kbGrpDSMFCATL kbNoUpdatekbbuglist kbfi
Last Modified: 06-MAY-2001

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

- The Microsoft Foundation Classes (MFC), used with:
   - Microsoft Visual C++ 32-bit Edition, version 2.0 
-------------------------------------------------------------------------------

SYMPTOMS
========

Attempting to undock or tear off a toolbar window from its dockbar window
occasionally causes the toolbar to disappear when the mouse button is released.

CAUSE
=====

This is caused by a bug in the MFC source code for CFrameWnd::CanDock().
Essentially, what happens is that the toolbar is being docked to an invisible
dockbar. The CFrameWnd::CanDock() function doesn't check to see if the new
docbar window is visible.

When you float a toolbar, and then close it by double-clicking the tiny control
menu or icon, the window is not destroyed; it is just hidden. If you happen to
drag and release another toolbar over the hidden toolbar, the toolbar being
dragged is docked to the hidden toolbar.

RESOLUTION
==========

To work around this problem, rebuild the project with Visual C++ version 2.1. If
that is not an option for you, you can work around the problem by modifying the
WINFRM2.CPP MFC source file and rebuilding the appropriate MFC library.

NOTE: Microsoft recommends against rebuilding the MFC30(D).DLL (the MFC Shared
DLL). MFC30(D).DLL is a common component of many MFC applications. Rebuilding
MFC30(D).DLL runs the risk of breaking other applications that rely on this
component. If you do rebuild MFC30(D).DLL, please rename the DLL.

Steps to fix WINFRM2.CPP Directly
---------------------------------

1. Replace following line of code in CFrameWnd::CanDock():

        if (pDockBar->IsDockBar() &&
           (pDockBar->m_dwStyle & dwDockStyle & CBRS_ALIGN_ANY) &&
           (!pDockBar->m_bFloating ||
        (dwDockStyle & pDockBar->m_dwStyle & CBRS_FLOAT_MULTI)))

  with this code:

        if (pDockBar->IsDockBar() && pDockBar->IsWindowVisible() &&
           (pDockBar->m_dwStyle & dwDockStyle & CBRS_ALIGN_ANY) &&
           (!pDockBar->m_bFloating ||
           (dwDockStyle & pDockBar->m_dwStyle & CBRS_FLOAT_MULTI)))

2. Rebuild the MFC library according to the instructions in the
  ..\MSVC\MFC\SRC\README.TXT file.

STATUS
======

Microsoft has confirmed this to be a bug in the Microsoft products listed at the
beginning of this article. This problem was corrected in Visual C++, 32-bit
Edition, version 2.1.

Additional query words: 2.00 3.0 3.00 CToolbar CDockBar

======================================================================
Keywords          : kbMFC kbToolbar KbUIDesign kbVC200bug kbVC210fix kbGrpDSMFCATL kbNoUpdate kbbuglist kbfixlist
Technology        : kbAudDeveloper kbMFC
Version           : winnt:
Issue type        : kbbug
Solution Type     : kbfix

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

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Q134283: FIX: Undocking Toolbar May Disappear When Removed from Dockbar