int modelIndex = modelCount - 1;
BitSet bs = new BitSet();
if (models[modelIndex].isTrajectory || models[modelIndex].getGroupCount() > 1)
return bs; // can't add atoms to a trajectory or a system with multiple groups!
growAtomArrays(atomCount + pts.length);
RadiusData rd = viewer.getDefaultRadiusData();
short mad = getDefaultMadFromOrder(1);
for (int i = 0, n = models[modelIndex].atomCount + 1; i < vConnections.size(); i++, n++) {
Atom atom1 = (Atom) vConnections.get(i);
// hmm. atom1.group will not be expanded, though...
// something like within(group,...) will not select these atoms!