VSTO for Outlook FormRegions and EnableActiveX=0

Question

I have a weird issue that I recently observed. A prospect had disabled all ActiveX on their computers with the EnableActiveX=0 GPO option. Should be quite common case, right? :)

It turns out that my developed Outlook Add-in (a FormRegion) now doesn't load the FormRegion and pops up with "To help prevent malicious code from running, on or more objects in this form were not loaded…" Funny thing is that I don't (as far as I know) use any ActiveX components.

I have even tried making a new VSTO Outlook FormRegion project in Visual Studio without anything but writing to the console log.

It seems to execute the FormRegionInitializing method fine, but the error message popups up immediately when entering the FormRegionShowing method.

I haven't been able to find an explanation by googling or anything - other than it seems as VSTO is simply wrapping forms into ActiveX to show them in Office... hmm..

Have you seen this before? And if so, have you found a workaround?

A MILLION THANKS!

• Michael

Answer 1

Form regions (as well as task bars) are implemented as ActiveX controls. If ActiveX controls are blocked, none of that would work.

Despite what some IT admins think, ActiveX controls are much more than a security thread to be squashed.