Not sure if you're looking for suggestions on GameGuru MAX's UI ... but here we go. And to make it more complex, it's not really a UI thing, but more of a "where things are put" and "what they are called".
Currently, to get to and place lights, you have to click the Entities button and then the Entities panel appears. Once there, you have to click on the Markers tab to access markers. Within are lights and spotlights.
Two things get me here - 1) clicking on Entities to get to Markers seems off to me and 2) I'd never think of looking in Markers to access lights.
Clicking on Entities to get to Markers just doesn't work, in my opinion. Markers are enough of a separate thing to have their own tab (as they do). Yet, the button we click to access them is only labeled as "Entities" on the main UI. You have to sort of stumble upon this (if you've not watched a video or read up on it) to find Markers from the main UI. And that means this is not intuitive. In my opinion, either there should be a separate button for Markers (from Entities) or the Entities button should be renamed to something that encompasses both Entities and Markers. I'm a big fan of being able to do as much as possible in a program as intuitively as possible. Hiding Markers within Entities is not, in my opinion, intuitive.
Secondly, I don't consider Lights to be markers. Sure, you are placing a "marker" to indicate where a light is. And, in retrospect, I think that makes some sense. However, most people coming at GameGuru MAX for the first time would be looking for something called "Lights" instead of "Markers" and I think it could frustrate them if lights are not easy to find (especially since they are such an essential part of map building). No other 3D editor I know, whether for games or for 3D modeling, calls "Lights" "Markers". Therefore, I think that Lights should be their own thing in the GameGuru MAX UI. In fact, it might be good to simply have a light bulb icon on the top toolbar and the end-user clicks it to access various lights and controls for those lights on the right-side panel (just like you do for the terrain tools, etc). So, this way, Lights are totally removed from the Markers panel and become a simple icon on the top toolbar.
Thoughts?