Something wrong with JBList

While working with JBList, I place it into the central area of a JPanel that uses a BorderLayout.

When the list has few entries, a click on the empty area beneath the last element is interpreted as a click on that last item.

Can someone explain what might be causing this behavior and guide me on the correct usage of JBList?

The code just like:

DefaultListModel<String> dataModel = new DefaultListModel<>();
dataModel.addElement("one");
dataModel.addElement("two");
dataModel.addElement("three");
JBList<String> testJBList = new JBList<>(dataModel);
JBLoadingPanel mainPanel = new JBLoadingPanel(new BorderLayout(), this, 0);
mainPanel.setVisible(true);
mainPanel.add(testJBList,BorderLayout.CENTER);

And click to empty area，“three” will be selected：