IAtom endAtom = null;
if(closestAtom != null && closestAtom.getPoint2d().distance(worldCoord) < dH)
endAtom = chemModelRelay.getClosestAtom(worldCoord);
if(endAtom!=null && startAtom!=null){
IMapping mapping = startAtom.getBuilder().newInstance(IMapping.class,startAtom, endAtom);
// ok, now figure out if they are in one reaction
IReaction reaction1 = ChemModelManipulator.getRelevantReaction(chemModelRelay.getIChemModel(), startAtom);
IReaction reaction2 = ChemModelManipulator.getRelevantReaction(chemModelRelay.getIChemModel(), endAtom);
if (reaction1 != null && reaction2 != null && reaction1 == reaction2)
{