// qt includes
#include <QtWidgets\QApplication>
#include <QtWidgets\QMainWindow>
#include <QtWidgets\QMenu>
#include <QtWidgets\QMenuBar>
#include <QtWidgets\QAction>
#include <QtWidgets\QLayout>

void AboutToShow( QMenu* pMenu )
{
	// randomly assign some to not visible
	for ( int a = 0; a < pMenu->actions().size(); a++ )
	{
		bool isVisible = (rand() % 4) > 0;
		pMenu->actions().at( a )->setVisible( isVisible );
	}

	// question posted to: https://forum.qt.io/topic/68765/how-to-update-geometry-on-qaction-visibility-change-in-qmenu-abouttoshow

	// attempt to update the geometry/placement of the menu
	//pMenu->parentWidget()->updateGeometry(); // doesn't work
	//pMenu->parentWidget()->update(); // doesn't work
	//pMenu->parentWidget()->updateGeometry(); // doesn't work
	//pMenu->parentWidget()->adjustSize(); // doesn't work
	//pMenu->parentWidget()->ensurePolished(); // doesn't work
	//pMenu->update(); // doesn't work
	//pMenu->updateGeometry(); // doesn't work
	//pMenu->adjustSize(); // doesn't work
	//pMenu->ensurePolished(); // doesn't work
	//pMenu->adjustSize(); // doesn't work
	//pMenu->parentWidget()->adjustSize(); // doesn't work
	//pMenu->parentWidget()->layout()->invalidate(); // no layout present
	//pMenu->layout()->invalidate(); // no layout present
}

int main(int argc, char *argv[])
{
	// setup application

	QApplication app(argc, argv);
	QMainWindow mainWin;
	mainWin.setMinimumSize( 500, 250 );
	mainWin.move( 1000, 1450 ); // low down

	// set up menus

	int numMenus = rand() % 5 + 3;
	int actionCount = 0;
	for ( int m = 0; m < numMenus; m++ )
	{
		QMenu* pMenu = mainWin.menuBar()->addMenu( QString().sprintf( "Menu %d", m ) );

		// add actions
		int numActions = rand() % 10 + 5;
		for ( int a = 0; a < numActions; a++ )
		{
			QAction* pAction = pMenu->addAction( QString().sprintf( "Action %d", actionCount++ ) );
		}
		app.connect( pMenu, &QMenu::aboutToShow, [=]() { AboutToShow( pMenu ); } );
	}

	// show and display

	mainWin.show();
	int result = app.exec();

	return result;
}