#include <QtWidgets>

class Widget: public QWidget
{
public:
    Widget(QWidget *parent = 0) : QWidget(parent)
    {
        QVBoxLayout *vbox = new QVBoxLayout(this);
        vbox->addWidget(new QSpinBox);
        vbox->addWidget(new QDoubleSpinBox);

        // With this stylesheet, the height computation for the spinbox
        // is wrong (even if the stylesheet has nothing to do with
        // the spinbox, as you can see.
        setStyleSheet(" ");
    }
};

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    Widget w;
    w.show();

    return a.exec();
}