Native GTK+ 3.x dialogs: improper signal emission

#include <QtWidgets>

//#define DONT_USE_NATIVE_DIALOGS

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

    QColorDialog colorDialog;
#ifdef DONT_USE_NATIVE_DIALOGS
    colorDialog.setOption(QColorDialog::DontUseNativeDialog);
#endif
    QObject::connect(&colorDialog, &QColorDialog::colorSelected, [](const QColor &c) { qDebug() << "QColorDialog::colorSelected" << c; });
    QObject::connect(&colorDialog, &QColorDialog::currentColorChanged, [](const QColor &c) { qDebug() << "QColorDialog::currentColorChanged" << c; });
    colorDialog.show();

    QFontDialog fontDialog;
#ifdef DONT_USE_NATIVE_DIALOGS
    fontDialog.setOption(QFontDialog::DontUseNativeDialog);
#endif
    QObject::connect(&fontDialog, &QFontDialog::fontSelected, [](const QFont &f) { qDebug() << "QFontDialog::fontSelected" << f; });
    QObject::connect(&fontDialog, &QFontDialog::currentFontChanged, [](const QFont &f) { qDebug() << "QFontDialog::currentFontChanged" << f; });
    fontDialog.show();

    QFileDialog fileDialog;
#ifdef DONT_USE_NATIVE_DIALOGS
    fileDialog.setOption(QFileDialog::DontUseNativeDialog);
#endif
    QObject::connect(&fileDialog, &QFileDialog::fileSelected, [](const QString &f) { qDebug() << "QFileDialog::fileSelected" << f; });
    QObject::connect(&fileDialog, &QFileDialog::currentChanged, [](const QString &f) { qDebug() << "QFileDialog::currentChanged" << f; });
    QObject::connect(&fileDialog, &QFileDialog::directoryEntered, [](const QString &f) { qDebug() << "QFileDialog::directoryEntered" << f; });
    fileDialog.show();

    return app.exec();
}

import QtQuick 2.5
import QtQuick.Window 2.2
import QtQuick.Dialogs 1.2

Window {
    width: 640
    height: 480
    visible: false

    ColorDialog {
        visible: true
        onColorChanged: console.log("onColorChanged:", color)
        onCurrentColorChanged: console.log("onCurrentColorChanged:", currentColor)
    }

    FontDialog {
        visible: true
        onFontChanged: console.log("onFontChanged:", font)
        onCurrentFontChanged: console.log("onCurrentFontChanged:", currentFont)
    }

    FileDialog {
        visible: true
        onFileUrlChanged: console.log("onFileUrlChanged:", fileUrl)
        onFileUrlsChanged: console.log("onFileUrlsChanged:", fileUrls)
    }
}