public void actionPerformed(ActionEvent e) {
   JTabbedPane pane = (JTabbedPane) e.getSource();
   CloseTabPaneUI ui = (CloseTabPaneUI) pane.getUI();
   int tabPlacement = pane.getTabPlacement();
   if (tabPlacement == TOP || tabPlacement == BOTTOM) {
     ui.navigateSelectedTab(EAST);
   } else {
     ui.navigateSelectedTab(SOUTH);
   }
 }
 public void actionPerformed(ActionEvent e) {
   JTabbedPane pane = (JTabbedPane) e.getSource();
   CloseTabPaneUI ui = (CloseTabPaneUI) pane.getUI();
   ui.navigateSelectedTab(PREVIOUS);
 }