Widgets doesn't respect application palette (MacOSX 10.6.8/Cocoa)

 
#include <QLabel>
#include <QApplication>

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

    QPalette palette = a.palette();


    palette.setColor(QPalette::WindowText, Qt::white);
    palette.setColor(QPalette::Button, Qt::white);
    palette.setColor(QPalette::Light, Qt::white);
    palette.setColor(QPalette::Dark, Qt::white);
    palette.setColor(QPalette::Text, Qt::white);
    palette.setColor(QPalette::Base, Qt::white);
    palette.setColor(QPalette::Window, Qt::black);
    palette.setColor(QPalette::HighlightedText, Qt::white);
    palette.setColor(QPalette::Highlight, Qt::white);
    palette.setColor(QPalette::Midlight, Qt::white);
    palette.setColor(QPalette::Mid, Qt::white);
    palette.setColor(QPalette::BrightText, Qt::white);
    palette.setColor(QPalette::ButtonText, Qt::white);
    palette.setColor(QPalette::Shadow, Qt::white);
    palette.setColor(QPalette::AlternateBase, Qt::white);
    palette.setColor(QPalette::ToolTipBase, Qt::white);
    palette.setColor(QPalette::ToolTipText, Qt::white);

    a.setPalette(palette);

    QLabel label("Test Label");
    label.show();
    //label.setPalette(a.palette());

    return a.exec();
}