The DBusCall is exported as a QObject to the QML environment. It is
intended as a declarative replacement for the callDBus method which used
to be exported on global scope in the QtQuick 1 world.
Example usage:
DBusCall {
id: dbus
service: "org.kde.KWin"
path: "/KWin"
method: "setCurrentDesktop"
arguments: [1]
Component.onCompleted: dbus.call()
}