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() );