public Object execute(ExecutionEvent event) throws ExecutionException {
String cheatSheetId = event.getParameter(PARAM_ID_CHEAT_SHEET_ID);
if (cheatSheetId == null) {
CheatSheetCategoryBasedSelectionAction action = new CheatSheetCategoryBasedSelectionAction();
action.run();
} else {
OpenCheatSheetAction action = new OpenCheatSheetAction(cheatSheetId);
action.run();
}
return null;
}