[opendx-users] how to create a legend for glyphs?

[Noah Knowles]

Hi, I have an animation that shows a time series of earthquakes on a map of 
California as glyphs (circles) whose sizes correspond to the quakes' 
magnitudes.

I would like to add a legend that shows 3 or 4 glyphs of increasing size 
with appropriate magnitude text labels. I want to do this in screen coords 
so I can move the earthquake map around (zoom and pan the camera) without 
moving the legend. To my knowledge, I can't do this with the provided 
screen objects such as Legend.

Looking through the archives, it seems that screen objects are somewhat of 
a can of worms, and I couldn't find any solution except that a Screen 
Object module was once included in DX in the past. Then again, I'm 
relatively new to this so I guess I might be missing something obvious. 
Suggestions?

Thanks.
nk