## BUG: Breakpoint on WM_MDIACTIVATE Code Maximizes Windows

Q108290

    1.00 1.50 1.51 1.52
    WINDOWS
    kbtool kbbuglist

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

     - The Visual Workbench Integrated Debugger, included with:
        - Microsoft Visual C++ for Windows, versions 1.0, 1.5, 1.51, and 1.52
    -------------------------------------------------------------------------

    SYMPTOMS
    ========

    Setting a breakpoint in the Visual Debugger on code executed as a result of
    a WM_MDIACTIVATE message causes the window in the application to be
    maximized.

    RESOLUTION
    ==========

    Use CodeView for Windows to debug the application instead of the Visual
    Debugger.

    STATUS
    ======

    Microsoft has confirmed this to be a bug in the Microsoft products
    listed at the beginning of this article. We are researching this
    problem and will post new information here in the Microsoft Knowledge
    Base as it becomes available.

    This problem does not occur in the 32-bit debugger.

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

    To reproduce the problem, follow these steps:

     1. Modify the BLANDMDI sample program in the \MSVC\SAMPLES\BLANDMDI
        directory. Add the following code to the beginning of the
        BlandMdiChildWndProc() function in the BLANDMDI.C source file:

           switch (msg)  {
             case WM_MDIACTIVATE:
               if (wParam == TRUE ) {}
           }

    2. Load the project in the Visual Workbench. Select Project, choose Open,
       and enter <path>\BLANDMDI.MAK.

     3. Rebuild the application. Select Project and choose Rebuild All.

     4. Set a breakpoint on the line of code containing

           if (wParam == TRUE) {}

        by placing the cursor on that line and pressing the F9 key.

     5. Press F5 to run; the code will execute to the breakpoint.

     6. Press F5 to continue executing.

     7. Select File and choose New.

     8. Press F5 to continue executing.

     9. Press F5 to continue executing.

    10. Click once in the title bar of the "Initial Window" of the Blandmdi
        application.

    11. Press F5 to continue executing.

    12. Press F5 to continue executing.

    13. The Initial Window is now incorrectly maximized. The only way to view
        the "Untitled" windows is by selecting the Window menu option and
        choosing Untitled.

    Additional reference words: 1.00 1.50
    KBCategory: kbtool kbbuglist
    KBSubcategory: WBDebug

Keywords : kb16bitonly
Issue type : kbbug
Technology : kbVCsearch kbAudDeveloper

Last Reviewed: May 5, 2001 © 2001 Microsoft Corporation. All rights reserved. Terms of Use.