Define editor radius on custom activator?

[PAPVAFS11]

I've got an activator I'm using to set up music zones. These have a maximum range that defines where the player will hear the music, and when it will fade away. It's difficult to guess at the distances I need without a visual guide, so I often need to go in-game and do distance checks to be sure the music covers the area I want it to.

So, is there any way to make its marker display a (customizable) radius in the render window, like some others do?