private void renderEditorArrows() { Iterator<AbstractLazyStackPanelHeader> iterator = factModelsPanel.getHeaderIterator(); while (iterator.hasNext()) { AbstractLazyStackPanelHeader widget = (AbstractLazyStackPanelHeader) iterator.next(); if (widget instanceof FactModelEditor) { FactModelEditor editor = (FactModelEditor) widget; int index = factModels.indexOf(editor.getFactModel()); editor.setUpVisible(index != 0); editor.setDownVisible(index != (factModels.size() - 1)); } } }