added overload to Entity.selection that accepts a string:

ent.selection='aname=CA'

is equivalent to

ent.selection=ent.view.Select('aname=CA')

t.py

+import desost_util
+e=io.LoadPDB("examples/demos/data/sh2.pdb")
+desost_util.RunStride(e,True)
+scene.Add(gfx.Entity("t",gfx.HSC,e))
+