When you hit “select (all) idle unit(s)”, units that have been told to stand their ground are selected as well.
Except the player has given them an active job stay there, they ain’t no idle bum.
What it gets us:
Prelates can be told to stay on eco
Scouts can be told to stay scouting at a location
Units can be told to guard a location(early pressure) (I guess you can do similar with patrol here, but baitable)
It’s a one-condition fix to a few UI issues