I've been using the new mask tool to extract features along surfaces, which is useful in its own right for generating separate maps of segmented areas. but, if I wish to color a region around a surface (or between surfaces) without generating a new map, I am not sure how to do this - the 'zone' and 'color zone' tools in Volume viewer expect atoms or marker files. I had thought about loading multiple files of these surface regions after segmenting them out, each with their own color, but loading them together produces the ordering problem with the volume rendering. also, loading multiple volumes consumes a lot of memory and I run short of memory. is there currently a way to color arbitrary regions in a volume rendering? for example, rendering all data within 60 A of a surface with a different color than the rest of the volume, or coloring a region between two surfaces a different color, analogous to the 'sandwich' option of the mask tool. thanks, -Jeff