32 bits IE Toolbar not working in Win 8.1 64 bits RTM/IE11

Question

I'm trying to update a 32 bits IE toolbar to work under Win 8.1 64 bits RTM/IE11.

Without any specific change, my toolbar is seen as "incompatible" by IE11 and is disabled.

I've discovered this is because Enhanced Protected Mode is activated by default on IE11 (I could have been in same situation with Win 8 if EPM was activated in IE10). If I desactivate EMP in IE>Internet Options>Advanced>Security, my toolbar works as expected. But because this option is ie wide (it's applied to every BHO, toolbar and ActiveX), it's not a viable workaround.

I've seen Eric Law's Understanding Enhanced Protected Mode, but I've yet several questions:

1. Is there a way to deactivate EPM for only one toolbar?
2. What are the requirements to support EPM?
   • Be registered as CATID_AppContainerCompatible?
   • Have both 32 and 64 bits binaries (is it mandatory)?
   • Use localhost instead of 127.0.0.1 if I need to communicates with already running proces on same machine?
   • Prevent any access to local ressources (file, registry, ...) either in write or in read?
   • What else?

Which constraint will apply to IE11 under Windows 7 (no AppContainer)?

Answer 1

This is by-design, as my blog you cited notes.

• Yes, you must include both 32bit and 64bit versions of your code when running on 64bit PCs even in a 32bit process.
• Yes, you must register in the AppContainerCompatible category.
• All resource ACL'ing restrictions apply (e.g. don't expect READ access to the registry or filesystem).
• Loopback network connections will always fail

Answer 2

8.1 runs browser in 64 bit. You will have to wait until the toolbar programmers release a 64 bit version.