plot1.addRangeMarker(1, new ValueMarker(4.0), Layer.FOREGROUND);
        assertFalse(plot1.equals(plot2));
        plot2.addRangeMarker(1, new ValueMarker(4.0), Layer.FOREGROUND);
        assertTrue(plot1.equals(plot2));
        
        plot1.addRangeMarker(1, new ValueMarker(99.0), Layer.BACKGROUND);
        assertFalse(plot1.equals(plot2));
        plot2.addRangeMarker(1, new ValueMarker(99.0), Layer.BACKGROUND);
        assertTrue(plot1.equals(plot2));