Same as D28507
Disable screen edge modification, but allow the user to open an edge context menu and see the settings.
To set an edge immutable, just add `[$i]` right after the entry in `ElectricBorders` group, although the edges settings are shared between some `[Effect-something]` group under the key `BorderActivateSomething`.
Since one entry like `BorderActivateSomething` lists all edges that use this effect, it doesn't make sense to set it immutable.