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Q221749: FIX: Top Level Forms with Menus Allow Access to Datasession 0

Article: Q221749
Product(s): Microsoft FoxPro
Version(s): WINDOWS:5.0,5.0a,6.0
Operating System(s): 
Keyword(s): kbContainer kbCtrl kbvfp500aBUG kbvfp600 kbvfp600bug KbDBFDBC kbVS600sp3fix kbGrpDSFox
Last Modified: 09-JUL-1999

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

- Microsoft Visual FoxPro for Windows, versions 5.0, 5.0a, 6.0 
-------------------------------------------------------------------------------

SYMPTOMS
========

You have an application based on a top-level form, which runs several child
forms that are called from a menu. One of these forms contains a grid. If the
table or cursor that is the grid's RecordSource is closed and then another form
is instantiated, the system datasession will be selected and Visual FoxPro will
be placed in an unstable state.

STATUS
======

Microsoft has confirmed this to be a bug in the Microsoft products listed at the
beginning of this article.

This bug was corrected in Visual Studio 6.0 Service Pack 3.

For more information about Visual Studio service packs, please see the following
articles in the Microsoft Knowledge Base:

  Q194022 INFO: Visual Studio 6.0 Service Packs, What, Where, Why

  Q194295 HOWTO: Tell That Visual Studio 6.0 Service Packs Are Installed

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

The system datasession is used by Visual FoxPro to open the Foxuser resource
file, form and class library files, report files, and so forth. It should not be
accessible to the user under any circumstances. If the system datasession
becomes selected, closing tables in it will cause Visual FoxPro to produce
errors or terminate.

Steps to Reproduce Behavior
---------------------------

1. Run the following code from a program (.PRG) file:

  PUBLIC oGrid, oMain
     * Make Form2 - it must be an SCX.
     MODIFY FORM form2 NOWAIT
     = aselobj(xx,1)
     xx[1].ShowWindow = 1   && Make it In Top-Level
     KEYBOARD '{y}'
     Release window 'form designer - form2.scx'

     * Create a table and add some data
     CREATE TABLE TEMP(TEMP1 C(6), TEMP2 C(6))  
     INSERT INTO TEMP (TEMP1, TEMP2) ;
     VALUES ("FIELD1", "FIELD2")

     CLOSE DATA ALL && Clean Start, no open tables open to start.

     oMain = CREATEOBJECT('MAIN')  && Top-level form
     oMain.Show
     READ events
     WAIT window 'DataSession Number is: '+alltr(str(set('datasession')))
     * Let's avoid problems and go back to datasession 1
     SET DATASESSION TO  1
     CLOSE DATA ALL

     DEFINE CLASS grid1 AS form
         ShowWindow = 1
         Caption = "GRID1"
         Name = "GRID1"
         ADD OBJECT grid1 AS grid WITH ;
             ColumnCount = 2, ;
             Name = "Grid1"
     ENDDEFINE

     DEFINE CLASS main AS form
         ShowWindow = 2
         Caption = "Click on Grid Form menu item"
         Name = "MAIN"

         PROCEDURE Show
             LPARAMETERS nStyle
             DO MenuProc WITH thisform,.T.
         ENDPROC

         PROCEDURE queryunload
             Clear events
         ENDPROC
     ENDDEFINE

     PROC MenuProc
         LPARAMETERS oFormRef, getMenuName
        	DEFINE MENU MyMenu IN (oFormRef.name) BAR
     	DEFINE PAD Pad1 OF MyMenu PROMPT "Grid Form" COLOR SCHEME 3 ;
     	    KEY ALT+C, ""
     	ON SELECTION PAD Pad1 OF MyMenu ;
     	    DO Proc1
     	DEFINE PAD Pad2 OF MyMenu PROMPT "Form 2" COLOR SCHEME 3 ;
     	    KEY ALT+F, ""
     	ON SELECTION PAD Pad2 OF MyMenu ;
     	    DO Proc2
     	Activate MENU MyMenu NOWAIT
     ENDPROC

     PROCEDURE Proc1
         SELECT 0
         USE TEMP alias TEMP
         SELECT TEMP
         oGrid=create('grid1')
         oGrid.show
         oMain.Caption = 'Click on Form2 menu item'
     ENDPROC

     PROCEDURE Proc2
         SELECT TEMP
         USE
         oGrid.release
         DO form form2
         oMain.Caption = "Click on Close Box to close =====>"
     ENDPROC

2. Click on the Grid Form menu pad.

3. Click on the Form 2 menu pad.

4. Click on the close box in the main form.

5. A WAIT WINDOW will be displayed with the current Datasession, which will be
  0.

(c) Microsoft Corporation 1999, All Rights Reserved. Contributions by Jim
Saunders, Microsoft Corporation.


Additional query words:

======================================================================
Keywords          : kbContainer kbCtrl kbvfp500aBUG kbvfp600 kbvfp600bug KbDBFDBC kbVS600sp3fix kbGrpDSFox kbDSupport 
Technology        : kbVFPsearch kbAudDeveloper kbVFP500 kbVFP600 kbVFP500a
Version           : WINDOWS:5.0,5.0a,6.0
Issue type        : kbbug
Solution Type     : kbfix

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

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