REG: Webkit printing graphics incorrectly to pdf

#include <QApplication>
#include <QWebView>
#include <QWebFrame>
#include <QPrinter>
#include <QBuffer>

class WebView : public QWebView
{
public:
    WebView()
        : QWebView(0)
    {
        load(QUrl("http://www.highcharts.com/demo/"));
    }
    void mousePressEvent(QMouseEvent *)
    {
        QWebFrame *const mainFrame = page()->mainFrame();
        QBuffer device;
        QByteArray m_Buffer;
        device.setBuffer(&m_Buffer);
        device.open(QIODevice::WriteOnly);
        QPrinter printer;
        printer.setOutputFormat(QPrinter::PdfFormat);
        printer.setPageSize(QPrinter::A4);
        QString filename;
        filename = "webpage.pdf";
        printer.setOutputFileName(filename);
        mainFrame->print(&printer);
    }
};

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    WebView w;
    w.show();
    return a.exec();
}