void (@NotNull AnActionEvent e) { Project project = e.getData(CommonDataKeys.PROJECT); if (project == null) return; // Ask group name final String groupName = Messages.showInputDialog( project, UIDesignerBundle.message("message.enter.group.name"), UIDesignerBundle.message("title.add.group"), Messages.getQuestionIcon() ); if (groupName == null) { return; } Palette palette = Palette.getInstance(project); // Check that name of the group is unique List<GroupItem> groups = palette.getGroups(); for (int i = groups.size() - 1; i >= 0; i--) { if (groupName.equals(groups.get(i).getName())) { Messages.showErrorDialog(project, UIDesignerBundle.message("error.group.name.unique"), CommonBundle.getErrorTitle()); return; } } final GroupItem groupToBeAdded = new GroupItem(groupName); ArrayList<GroupItem> newGroups = new ArrayList<>(groups); newGroups.add(groupToBeAdded); palette.setGroups(newGroups); }