RyaReisender: Well if you are generally asking, I'd say that porting any kind of product to a different OS is quite a bit of work. If you write an editor for Windows you need to use certain window calls like "ShowWindow" "Add a button into the window at X,Y" and so on. These calls are all different on other operating systems, you will have to rewrite them. (That is assuming you are using windows forms for the editor.)

There are a few more global formats like the Java interface elements (but people don't really like Java anymore before it's opens up so many security gaps) and drawing graphics with DirectX (but using that to create an editor is probably overkill?), but in terms of work it's probably easiest to just get Visual Studio and use Windows Forms.

Now if you're making a game, then porting it to other OSs might be worth it because even if it takes 3 man months which amounts to $100000 expenses, it's still worth it if you can sell it 5000+ times for $20 on that system. Now with an editor, you usually won't really end up with "If we offer that editor on Mac, 5000 more people will buy the game", so it often is simply not worth the effort.

Note this is a general reply and does not necessarily need to be the reason for the LoX developer. I'm not even sure if he's working on porting it or not.