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
#!/bin/sh /usr/bin/metacity & /path/to/application
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.