a1.setTickLabelFont("C1", null);
        assertFalse(a1.equals(a2));
        a2.setTickLabelFont("C1", null);
        assertTrue(a1.equals(a2));
        
        // check that changing a tick label paint in a1 doesn't change a2
        a1.setTickLabelPaint("C1", Color.yellow);
        assertFalse(a1.equals(a2));
        a2.setTickLabelPaint("C1", Color.yellow);
        assertTrue(a1.equals(a2));

        // check that changing a category label tooltip in a1 doesn't change a2
        a1.addCategoryLabelToolTip("C1", "XYZ");
        assertFalse(a1.equals(a2));
        a2.addCategoryLabelToolTip("C1", "XYZ");
        assertTrue(a1.equals(a2));