else if (w == LengthConstraintType.RANGE) {
            // find optimum width and map to range
            if (h == LengthConstraintType.NONE) {
                // find optimum height
                throw new RuntimeException("Not yet implemented.");  
            }
            else if (h == LengthConstraintType.FIXED) {
                // fixed width
                throw new RuntimeException("Not yet implemented.");  
            }
            else if (h == LengthConstraintType.RANGE) {
                throw new RuntimeException("Not yet implemented.");