To be precise: you need to drop your stage elements in the parameter called "Elements".
There are two modes:
- If 'Exclude' is disabled, it means "Elements is the list of sub-trees that will be impacted by the virtual screen"
- If 'Exclude' is enabled, it means "Everything will be impacted by the virtual screen, except the list of sub-trees in the Elements parameter"
In all cases, the resulting list of led screens and surfaces will be displayed in the "Impacted Elements" parameter.
It's a bit ugly and we have an issue on this since some amount of time, I know