DOCUMENT:Q158765  20-AUG-1999  [foxpro]
TITLE   :INFO: NODUALINTERFACE Entry is Placed in Registry by VFP 5.0
PRODUCT :Microsoft FoxPro
PROD/VER:
OPER/SYS:
KEYWORDS:kbsetup kbvfp500 kbvfp600

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The information in this article applies to:

 - Microsoft Visual FoxPro for Windows, versions 5.0, 6.0 
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SUMMARY
=======

Some ActiveX controls can support early binding, that is, where the control
supports a dual interface (a combination of an IDispatch and a Vtable
interface). If an ActiveX control registers itself incorrectly as supporting a
dual interface, then it might produce incorrect error messages. These errors may
include Invalid Page Fault errors under Windows 95 or Access Violation errors
under Windows NT.

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

Some ActiveX controls might be incorrectly registered as supporting Vtable
binding. This might cause an error when you use an ActiveX control. Visual
FoxPro 5.0 addresses this error in the development environment by adding the
"NoDualInterface" key to the registry. This key lists three known controls that
can register themselves as supporting Vtable binding. Note that there may be
other Activex controls that register themselves as supporting Vtable binding
when, in fact, they do not. If you add them to this list, they function
properly.

When Visual FoxPro is used to build an .exe file, it does not add the
NoDualInterface key to the registry file upon installation. If an ActiveX
control does not perform correctly, use the SYS(2333) function to enable or
disable dual-interface support of an ActiveX control.

You can also build a .reg file and run it as a post-executable when you install
the .exe file. This adds the "NoDualInterface" key to the registry.

Or, you can write a program in Visual FoxPro that updates the registry.

REFERENCES
==========

For more information about how to write a program in Visual FoxPro to update the
registry, please see the following article in the Microsoft Knowledge Base:

   Q135398 How To Write to the Windows Registry Using API Calls

For more information about early binding, please see the following article in the
Microsoft Knowledge Base:

   Q138138 Three Binding Types (Late, ID, Early) Possible in VB for Apps

Currently, Visual FoxPro 5.0 is the only Microsoft product that supports the
early Vtable binding of an ActiveX control. To disable dual-interface
functionally of an ActiveX control, use the SYS(2333) function.


Additional query words:

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Keywords          : kbsetup kbvfp500 kbvfp600 
Technology        : kbVFPsearch kbAudDeveloper kbVFP500 kbVFP600
Issue type        : kbinfo

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