Q266363: BUG: Fatal Error When Closing Forms That Use DHTML Edit Control

Article: Q266363
Product(s): Microsoft FoxPro
Version(s): WINDOWS:6.0
Operating System(s): 
Keyword(s): kbDSupport kbCodeSnippet kbGrpDSFox kbActiveX kbCtrl kbvfp600 kbvfp600bug
Last Modified: 05-AUG-2000

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The information in this article applies to:

- Microsoft Visual FoxPro for Windows, version 6.0 
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SYMPTOMS
========

When you release a form being executed that contains a Dynamic HTML Edit Control
(DHTMLed.ocx), a fatal exception error may occur.

CAUSE
=====

The fatal exception error occurs when the _VFP.AutoYield property is set to
False (.F.). The fatal exception error may occur on Microsoft Windows 2000,
regardless of the setting of the _VFP.AutoYield property.

RESOLUTION
==========

When you execute forms that contain the Dynamic HTML Edit Control, set the
_VFP.AutoYield property to True (.T.).

NOTE: Setting the _VFP.AutoYield property to True (.T.) does not prevent the
occurrence of a fatal exception on Windows 2000.

STATUS
======

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

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

NOTE: The Microsoft Dynamic HTML Edit Control has not been tested with and may
not be supported by Microsoft Visual FoxPro.

This behavior does not occur when forms containing the Dynamic HTML Edit Control
are released on Microsoft Windows NT 4.0.

This behavior occurs when Microsoft Visual FoxPro forms that contain the Dynamic
HTML Edit Control are released on the Microsoft Windows 2000 Server, regardless
of the value of _VFP.AutoYield.

The Visual FoxPro Help Documentation indicates that the AutoYield property should
be set to False (.F.) when a form contains an ActiveX control. Setting AutoYield
to False (.F.) prevents events for an ActiveX control from executing between
lines of user program code.

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

1. Create a program file named "Dhtml.prg" (without the quotation marks), by
  using the following code:

  PUBLIC ox
  OldAutoYield=_VFP.AutoYield
  _VFP.AutoYield=.T.
  FOR i=1 TO 10
     ox=CREATEOBJECT("DEMO")
     ox.SHOW
     IF _VFP.AUTOYIELD
        WAIT WINDOW "AutoYield = TRUE" NOWA
     ELSE
        WAIT WINDOW "AutoYield = FALSE" NOWA
     ENDIF
     FOR EACH oform IN _SCREEN.FORMS
        oform.RELEASE
     ENDFOR
     IF i=5
        _VFP.AUTOYIELD=.F.
     ENDIF
  ENDFOR
  *!* Reset the AutoYield property to default
  _VFP.AUTOYIELD=OldAutoYield

  DEFINE CLASS demo AS FORM
     TOP = 0
     LEFT = 0
     AUTOCENTER = .T.
     HEIGHT = 454
     WIDTH = 633
     DOCREATE = .T.
     CAPTION = "Form1"
     NAME = "Form1"

     ADD OBJECT olecontrol1 AS OLECONTROL WITH ;
        TOP = 24, ;
        LEFT = 12, ;
        HEIGHT = 276, ;
        WIDTH = 612, ;
        NAME = "Olecontrol1", ;
        OLECLASS = "DHTMLEdit.DHTMLEdit.1"

     ADD OBJECT text1 AS TEXTBOX WITH ;
        VALUE = "http://www.msn.com", ;
        HEIGHT = 25, ;
        LEFT = 24, ;
        TOP = 408, ;
        WIDTH = 577, ;
        NAME = "Text1"

     ADD OBJECT command1 AS COMMANDBUTTON WITH ;
        TOP = 324, ;
        LEFT = 24, ;
        HEIGHT = 25, ;
        WIDTH = 145, ;
        CAPTION = "\<Navigate", ;
        NAME = "Command1"

  ENDDEFINE

2. Save and run the program file, and note that after the fifth iteration, a
  fatal exception error may occur.

REFERENCES
==========

For additional information, query the Visual FoxPro Help Files; search on
"AutoYield."
(c) Microsoft Corporation 2000, All Rights Reserved. Contributions by John Desch,
Microsoft Corporation.


Additional query words: DHTMLed AutoYield

======================================================================
Keywords          : kbDSupport kbCodeSnippet kbGrpDSFox kbActiveX kbCtrl kbvfp600 kbvfp600bug 
Technology        : kbVFPsearch kbAudDeveloper kbVFP600
Version           : WINDOWS:6.0
Issue type        : kbbug
Solution Type     : kbnofix

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