private boolean showDialogIsEmpty() {
   if (heap.isEmpty()) {
     Dialog.showInformation("Chyba", "Binární halda je prázdná.");
     return true;
   }
   return false;
 }
 private Dialog.Result showHeapType() {
   HeapType[] buttons = new HeapType[] {HeapType.MIN, HeapType.MAX};
   Dialog.CustomButtonsDialog<HeapType> dlg =
       Dialog.createCustomButtonsDialog(
           "Reset", "Vyberte typ nové haldy:", Dialog.Icon.QUESTION, buttons, true);
   Dialog.Result result = dlg.showDialog();
   if (result == Dialog.Result.OK) {
     heap = new BinaryHeap(eventBus, dlg.getResult());
     clear();
     controlsContainer.getStructureControls().enableButtons();
   }
   return result;
 }