C++/VB - DoModal() returns -1 in 64-bit executable

Asked By hecto

09-Jul-07 08:20 PM

Hi All,
I'm having a problem with creating a dialog with a 64-bit executable. The
issue is the following:
I have a dialog, derived from CDialog that I create and show using
DoModal(). This works fine when I compile and run in a 32-bit Vista
environment. But when I compile it for 64-bit Vista, the executable runs and
the constructor for my custom dialog gets called, but "DoModal()" returns -1
and the dialog never appears.
The msdn documentation for CDialog says that DoModal() returns -1 when a
dialog cannot be created, but that's not very specific.
Does anyone have any ideas as to what may be going wrong?
Thanks in advance and regards,

Hector.

09-Jul-07 10:22 PM

The most common cause for a failure in DoModal is putting a control on
the dialog that has not been registered.  ActiveX controls require
registration.  Many IE controls require a call to InitCommonControlsEx
before creating the dialog.

--
Scott McPhillips [MVP VC++]

10-Jul-07 09:29 AM

What sort of controls are in your dialog?  Are you running any ActiveX controls, or a rich
edit control?  It could be that the custom controls are not installed on your target
machine, e.g., you only have 32-bit versions of the custom controls and therefore they
cannot be used in a 64-bit app.

One way to discover if this is a problem is to go to your app, bring up the dialog, and
change the "No Fail Create" property to TRUE.  What should happen now is that the dialog
will be created but one or more controls will be missing.  The missing controls will be
the ones that don't have a 64-bit versions, or for which the 64-bit -bit version is not
properly installed.
joe


Joseph M. Newcomer [MVP]
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