Order elements in object tree also by class_id, e.g. first groups, then neurons
Order elements in object tree also by class_id, e.g. first groups, then neurons

fzadow/CATMAID,htem/CATMAID,htem/CATMAID,fzadow/CATMAID,fzadow/CATMAID,htem/CATMAID,fzadow/CATMAID,htem/CATMAID