When a mission gets a level of complication it becomes a giant mess of lines for waypoints, synched stuff, groupings.

It would be extremely useful to allow the user to work in layers in editor. The user would be able to hide/show/clear/merge-to different layers. Sort of like in Blender for example.

I would have different layers for units of different sides, for objects, for markers... The possibilities are endless.

Markers wouldn't have to be hidden automatically anymore when changing categories - sometimes you want them visible when adding other stuff and right now that's impossible - the user could just put them on a different layer by choice.

Example of usefulness: Say you want all objects in one mission merged into another mission. Now you basically have to delete everything else by holding down delete and brushing it away, sometimes accidentally deleting stuff you need requiring a do-over. With layers you would just clear all layers you don't need.