Thanks, Erel.
The fact that I could have more Activities, some with B4XPages and others not, and Activities with different orientations, "fortunately" I knew.
What I meant is that I couldn't just add an Activity with a different orientation than the one with the B4XPages in this case because, if the app was send to background, the Activity would lose any messages sent by a server, while using a "pair B4XPage + Activity ", I can solve the problem (the B4XPage will receive the messages, the Activity will show them).