Whenever you get around to improving the UI styling, if possible, please replace the up/down arrows with grab handles/grippers, like in the train schedule and technology GUIs. They're way easier for reordering things, and less visually intrusive.

I'd love to but couldn't find out how when I was making that part. I asked around now, it's not possible with the current mod API, all mods use some type of button scheme for this. https://forums.factorio.com/128960 https://forums.factorio.com/100481

You've probably seen this but just in case: you can press modifier keys to move the elements further.

I had my suspicions since popular mods like Factory Planner don't have grab handles. I hadn't seen the modifier keys thing, so thanks for that info.