Pretty small and simple request, but would make editing large complex worlds A LOT easier.
Would like to be able to right click on an actor in the World Outliner and select “Lock” (or “Freeze”). When an actor is locked or frozen, it is no longer selectable in the viewport. Clicking on it will not select it. Clicks will simply pass through it as if it wasn’t there allowing actors behind it to be selected instead.
When I’m working on levels, sometimes I would like to lock things like the terrain, sky and other background items, so that I don’t accidentally move them while I’m working. I sometimes also like to click away from the selected actor to get rid of the gizmo and selection outline, but doing so inadvertently selects the sky (or something else) and then the gizmo and selection outline appears in the background somewhere.
Right clicking on the actor in the World Outliner should then give you the option to “Unlock” (or “Unfreeze”) the actor. There should also be an option for “Unlock All” (or "Unfreeze All) too.
3ds max has this feature and it is fantastic when working in complex scenes.