Why does it have to be so complex and is a second Activity needed?
(I'm about to search on site how to have a full screen B4XPage, with "Immersive mode" too).
P.S. Setting #FullScreen = True - #IncludeTitle = False seems to show a "full screen B4XPage" (although I have to "remove" the rounded corners of Root some way, since: Root.SetColorAndBorder(Root.Color, 0, xui.Color_Transparent, 0)
it's not enough).
"Immersive mode"... I still have to try (I had problems with it even with non-B4XPages).