category.add(defaultMutableTreeNode);
defaultMutableTreeNode = new DefaultMutableTreeNode(new ChartInfo("AreaChart02 - Null Y-Axis Data Points", new AreaChart02().getChart()));
category.add(defaultMutableTreeNode);
defaultMutableTreeNode = new DefaultMutableTreeNode(new ChartInfo("AreaLineChart03 - Combination Are & Line Chart", new AreaLineChart03().getChart()));
category.add(defaultMutableTreeNode);
// Line category
category = new DefaultMutableTreeNode("Line Charts");
top.add(category);