[REG 4->5] Windows: QComboBox popup becomes "detached" if parent widget is scrolled with the mouse wheel

#include <QApplication>
#include <QLabel>
#include <QComboBox>
#include <QLayout>
#include <QScrollArea>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);

    // Create a layout
    auto layout = new QVBoxLayout();
    layout->setSizeConstraint( QLayout::SetMinAndMaxSize );

    // Add some labels for filler
    for( int i=0; i < 10; ++i )
    {
        layout->addWidget( new QLabel( "Blah" ) );
    }

    // Create a combobox and add to layout
    auto cmb = new QComboBox();
    cmb->addItems( QStringList() << "Won" << "Too" << "3" << "fore" );
    layout->addWidget( cmb );

    // Add some labels for filler
    for( int i=0; i < 10; ++i )
    {
        layout->addWidget( new QLabel( "Blah" ) );
    }

    // Put in a widget
    auto widget = new QWidget();
    widget->setLayout( layout );

    // Put in a scroll area
    auto scroll = new QScrollArea();
    scroll->setWidget( widget );
    scroll->show();

    return a.exec();
}