Source:
private MouseAdapter getMouseAdapter() { return new MouseAdapter() { private void handlePopupEvent(MouseEvent e) { JTree tree = (JTree) e.getSource(); TreePath path = tree.getPathForLocation(e.getX(), e.getY()); if (path == null) { return; } DefaultMutableTreeNode node = (DefaultMutableTreeNode) path.getLastPathComponent(); TreePath[] paths = tree.getSelectionPaths(); boolean isSelected = false; if (paths != null) { for (TreePath selectionPath : paths) { if (selectionPath.equals(path)) { isSelected = true; } } } if (!isSelected) { tree.setSelectionPath(path); } if (node.isLeaf()) { JPopupMenu popup = new JPopupMenu(); JMenuItem aboutRuleMenuItem = new JMenuItem(messages.getString("guiAboutRuleMenu")); aboutRuleMenuItem.addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent actionEvent) { RuleNode node = (RuleNode) tree.getSelectionPath().getLastPathComponent(); Rule rule = node.getRule(); Language lang = config.getLanguage(); if(lang == null) { lang = Languages.getLanguageForLocale(Locale.getDefault()); } Tools.showRuleInfoDialog(tree, messages.getString("guiAboutRuleTitle"), rule.getDescription(), rule, messages, lang.getShortCodeWithCountryAndVariant()); } }); popup.add(aboutRuleMenuItem); popup.show(tree, e.getX(), e.getY()); } } @Override public void mousePressed(MouseEvent e) { if (isCheckBoxClicked == false && lastPath != null && lastTree != null) { try { lastTree.getClass().getMethod("setState").invoke(lastTree, null); } catch (Exception e1) { e1.printStackTrace(); } } lastPath = null; isCheckBoxClicked = false; if (e.isPopupTrigger()) { handlePopupEvent(e); } } @Override public void mouseReleased(MouseEvent e) { if (e.isPopupTrigger()) { handlePopupEvent(e); } } }; }

Target:
private MouseAdapter getMouseAdapter() { return new MouseAdapter() { private void handlePopupEvent(MouseEvent e) { JTree tree = (JTree) e.getSource(); TreePath path = tree.getPathForLocation(e.getX(), e.getY()); if (path == null) { return; } DefaultMutableTreeNode node = (DefaultMutableTreeNode) path.getLastPathComponent(); TreePath[] paths = tree.getSelectionPaths(); boolean isSelected = false; if (paths != null) { for (TreePath selectionPath : paths) { if (selectionPath.equals(path)) { isSelected = true; } } } if (!isSelected) { tree.setSelectionPath(path); } if (node.isLeaf()) { JPopupMenu popup = new JPopupMenu(); JMenuItem aboutRuleMenuItem = new JMenuItem(messages.getString("guiAboutRuleMenu")); aboutRuleMenuItem.addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent actionEvent) { RuleNode node = (RuleNode) tree.getSelectionPath().getLastPathComponent(); Rule rule = node.getRule(); Language lang = config.getLanguage(); if(lang == null) { lang = Languages.getLanguageForLocale(Locale.getDefault()); } Tools.showRuleInfoDialog(tree, messages.getString("guiAboutRuleTitle"), rule.getDescription(), rule, messages, lang.getShortCodeWithCountryAndVariant()); } }); popup.add(aboutRuleMenuItem); popup.show(tree, e.getX(), e.getY()); } } @Override public void mousePressed(MouseEvent e) { if (isCheckBoxClicked == false && lastTree != null) { lastTree.setState(); } isCheckBoxClicked = false; if (e.isPopupTrigger()) { handlePopupEvent(e); } } @Override public void mouseReleased(MouseEvent e) { if (e.isPopupTrigger()) { handlePopupEvent(e); } } }; }