private boolean evaluateTrajectoryClause(String str) {
		if (str == null || str.equals(""))
			return false;
		boolean on = str.equalsIgnoreCase("on");
		int n = model.getAtomCount();
		if (n <= 0)
			return true;
		for (int k = 0; k < n; k++) {
			Atom a = model.getAtom(k);
			if (a.isSelected()) {
				model.view.showTrajectory(k, on);
			}
		}
		view.repaint();
		model.notifyChange();
		return true;
	}