Can't change geometry after going from fullscreen

#include <QApplication>
#include <QScreen>
#include <QWidget>
#include <QTimer>

int main(int argc, char *argv[]) {
	QApplication app(argc, argv);
	QWidget widget;
	widget.setScreen(QGuiApplication::primaryScreen());
	widget.setGeometry(QGuiApplication::primaryScreen()->geometry());
	widget.showFullScreen();
	QTimer::singleShot(1000, [&] {
		widget.showNormal();
		widget.resize(100, 100);
	});
	return app.exec();
}