1. Yes. In T:ANE, train tab is closed when the session opens, so no problem.
2. The session doesn't start in the place I want to place my train, so first I must open the map to select one, that's why the train tab must be closed otherwise the map won't open. Once the starting point is correct and the map closed, train tab is gone on its own, then I must click on "Edit Trains" to make it go back, I place rolling stock on track and close it. All operations (add, move, rotate, delete...) work as intended at this point. Say a few minutes later I decide to rotate it: as train tab has vanished, I click again on "Edit Trains", it opens, then I rotate my train, everything is OK, except train tab vanishes again when I close it to drive my train. Now if later I want to re-open train tab...
3.
(i) ...clicking on "Edit Trains" seems to have no effect (no train tab showing).
(ii) Cannot select anything as there is no train tab showing, but if I click on my train, it rotates: in fact, train tab is open in the background but invisible.