Regression: Mac: QDialog sizing and drawing issues

#include <QApplication>
#include <QDialog>
#include <QHBoxLayout>
#include <QLabel>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    QDialog w;
    QHBoxLayout *layout = new QHBoxLayout(&w);
    layout->addWidget(new QLabel("FOOOOO"));
    w.show();
    
    return a.exec();
}