A rootless application requires a windowing system handling the application’s window geometry, visibility, etc. (i.e. operations that you normally do by using the window frame on a desktop OS). This kind of window management is not offered by Android so running an application in rootless mode is not allowed.
When you run a custom session it automatically creates a virtual desktop, which explains why you don’t see two different options in the custom session configuration.
In order to run a custom application on mobile you have a couple of options.
· Run the application by using the ‘-geometry’ option, for example
/path/to/application -geometry wxh+0+0
where “w” and “h” are width and height of the screen of your Android device, and “+0+0” means that the origin of the window must be the origin of the display. The application will cover all the available area.
· Run a script executing a window manager and your application, for example
Replace “metacity” with the window manager you prefer. You can use the window manager to maximize the application’s window like you do on desktop.