Being able to set the PopupMode option for QAction without needing to know about the underlying widget.

The code below demonstrates how the PopupMode is currently set:

#include <QApplication>
#include <QMenu>
#include <QToolButton>
#include <QToolBar>
int main(int argc, char *argv[])

{     QApplication a(argc, argv);     QToolBar bar;     auto action = bar.addAction("Action");     QMenu* menu = new QMenu;     menu->addAction("Subaction");     action->setMenu(menu);     bar.show();     QWidget * widget = bar.widgetForAction ( action );     QToolButton* button = qobject_cast<QToolButton*>(widget);     button->setPopupMode(QToolButton::InstantPopup) ;     return a.exec();   }