Qt5.0 or newer-- how to create a transparent window use qml

[kern0516]

i googled some solution but only for qt 4.x
for example:
QmlApplicationViewer view;
view.setWindowFlags(Qt::FramelessWindowHint);
view.setAttribute(Qt::WA_TranslucentBackground);
view.setStyleSheet("background:transparent;");

and in qt 5.0 the view class is "QtQuick2ApplicationViewer"
how to use that, can anyone give me some help
some code snippet is best

thanks

[Vincent007]

opacity: 0

[kern0516]

thanks,

but this attribute might affect the items in this window
i want to show a png witch has shadow border

[Vincent007]

color: "#00000000" // ARGB fully transparent