Bug 93400 LTK UI should provide official API for structural content in the preview page
org.eclipse.ltk.ui.refactoring/src/org/eclipse/ltk/internal/ui/refactoring/PreviewWizardPage.java
private FilterDropDownAction fOwner;
		public ShowAllAction(FilterDropDownAction owner) {
			super(RefactoringUIMessages.PreviewWizardPage_showAll_text, IAction.AS_RADIO_BUTTON);
			super.setToolTipText(RefactoringUIMessages.PreviewWizardPage_showAll_description);
			fOwner= owner;
			setChecked(true);
		}
		public void run() {
			clearGroupCategories();
			fOwner.executed(this);
		}
	}
	private class FilterDropDownAction extends Action implements IMenuCreator {
		private Menu fMenu;
		private ShowAllAction fShowAllAction;
		private FilterAction[] fFilterActions;
		private Action fActiveAction;
		
		public FilterDropDownAction() {
			setImageDescriptor(RefactoringPluginImages.DESC_ELCL_FILTER);
			setDisabledImageDescriptor(RefactoringPluginImages.DESC_DLCL_FILTER);
			setMenuCreator(this);
		}
		public void initialize(Collection groupCategories) {
			fShowAllAction= new ShowAllAction(this);