Hello, I found myself constantly needing to re-center on different regions of EM density maps, and I was originally just dropping spheres on the surface, centering on those, then deleting them. Finally I got sick of that and wrote this. It will center the window on the surface of whatever surface the mouse is currently overlaying. I found this to be a very helpful addition when looking at large EM maps, and was thinking other people might too, after using it for a while I feel as though it could be part of trunk since I use it so much. basically it would require the addition of this to standard_accelerators.py ... other accelerators.. ('zx', 'Center view on surface where mouse is located', center_on_surface_at_mouse), ... zx because it's close to where you rest your hands on the keyboard... def center_on_surface_at_mouse(): from chimera import selection, tkgui hits = [] w = tkgui.app.graphics x = w.winfo_pointerx() - w.winfo_rootx() y = w.winfo_pointery() - w.winfo_rooty() from Surface import surface_models import VolumePath.tracer as tracer hits.extend(tracer.surface_intercepts(x, y, surface_models())) xyz, model = tracer.closest_hit(hits) print(xyz) if xyz: print('cofr %f,%f,%f' % (xyz[0],xyz[1],xyz[2])) chimera.runCommand('cofr %f,%f,%f' % (xyz[0],xyz[1],xyz[2])) chimera.viewer.camera.center = xyz cheers! ~Dan