Overriding ROM applications on 8.1

Hello y'all

We have some applications that override the phone built-in ones
in ROM. This has been working fine, we've just given them the
same UID as the built-in ones. Until 8.1 (specifically, Nokia's
N70 with Series 60 v2 FP3). Now clicking on the menu icon, or
calling RApaLsSession::StartDocument with application uid starts
the built-in application from ROM instead. If our application
is alrady running, it gets switched to, though.

Has something changed in the application architecture in 8.1?
Or is this a Nokia thing? What would be the way to re-enable
the old behaviour?

I've now implemented a work-around where our applications are
automatically started when the phone starts and moved
to the background when the user selects 'Exit' so that they
are always running and so get used. It's just not very friendly
to the user, who can't really exit the application and if the
user manages to open one of the built-in apps before our app
starts it gets closed from underneath them.

Cheers,
    Mika Raento