Access from C   to ListElement (QML) color
ListModel {
    id:myListModel
    ListElement {name:"one" ;color:"red";objectName:"first"}
    ListElement(name:"two";color:"green"}
}

QObject* o=ui->declarativeView->rootObject()->findChild<QObject*>("first");
  o->setProperty("color","blue");

ListModel {
    id:myListModel
    objectName: "model"
    function setColor(index, color) {
        myListModel.setProperty(index, "color", color)
    }
    ListElement {name:"one";color:"red"}
    ListElement {name:"two";color:"green"}
}

QObject* o=ui->declarativeView->rootObject()->findChild<QObject*>("model");
QMetaObject::invokeMethod(o, "setColor", Q_ARG(QVariant, 0), Q_ARG(QVariant, "yellow"));