How to effect the AreaDrop with "Qt::FramelessWindowHint" flag in Windows

MeowSprite

Hello guys, I am a newer to Qt. I wanna develop a framless application. But AreaDrop in QML doesnot work with the framless application in Windows.
my code:

//main.qml
import QtQuick 2.5

Item {
    visible: true
    width: 640
    height: 480

    Rectangle {
        anchors.fill: parent
        width: 640
        height: 480
        color: "green"

        DropArea {
            anchors.fill: parent
            width: 640
            height: 480
            onEntered: {
                console.log("drop enter")
            }

            onDropped: {
                console.log("droped");
            }
        }
    }
}

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

    QQuickView viewer;
    viewer.setSource(QUrl("qrc:/main.qml"));
    viewer.setFlags(Qt::FramelessWindowHint);
    viewer.setColor(QColor(Qt::transparent));
    viewer.show();
    return app.exec();
}

This code works fine in the Ubuntu, But in Windows, the file dropping is unacceptable .
So, how can I drag a file into the frameless application in Windows.
Thanks!!