I know there is already
a topic on this, but it is also better if it is posted in the Suggestions topic.
I would like level designers the option to be allowed to not have any background in their levels if they do not want. I've made some levels which I'm uncomfortable having a background on because of its distraction and that it doesn't look good, and changing its primary set to something that has a black background is a kludgy workaround.
If also (e.g.) I made a level in the City tileset (which has a background), and change the primary graphic set to Dirt (which has a black background) and I want to add objects/terrain from the City tileset, it will be a slight hassle as when I open the object/terrain menu, it will show Dirt pieces, and I have to scroll through the graphic set menu to access the City pieces.
It will also be very beneficial to those who use the Style Counter, and they want to know exactly how many City/Biolab/Abstract/etc. levels they made without the need to change the level's primary set to a graphic set without a background.
I would really like this feature to be added to NeoLemmix. It will be very beneficial for a lot of level designers and will simplify things greatly.