void toggleSelectionSet(BitSet bs) {
		/*
		 * toggle each one independently for (int i = viewer.getAtomCount(); --i >= 0; ) if (bs.get(i))
		 * toggleSelection(i);
		 */
		int atomCount = viewer.getAtomCount();
		int i = atomCount;
		while (--i >= 0)
			if (bs.get(i) && !bsSelection.get(i))
				break;
		if (i < 0) { // all were selected
			for (i = atomCount; --i >= 0;)
				if (bs.get(i))
					bsSelection.clear(i);
			empty = UNKNOWN;
		}
		else { // at least one was not selected
			do {
				if (bs.get(i)) {
					bsSelection.set(i);
					empty = FALSE;
				}
			} while (--i >= 0);
		}
		selectionChanged();
	}