GridView and ObjectModel. Highlight size and resize of dynamically added elements.

[bronstein87]

Hi. I have three questions about GridView and ObjectModel.
Here is a little example to explain my problems:

main.qml

import QtQuick 2.12
import QtQuick.Window 2.12
import QtQuick.Controls 2.12
import QtQml.Models 2.12
import QtQuick.Layouts 1.12


Window {
    visible: true
    width: 640
    height: 480
    title: qsTr("Hello World")
    Page
    {
        width: parent.width
        height: parent.height
        footer: Button{
            width: parent.width
            height:  100
            text: "test"
            function createObject()
            {

                var component = Qt.createComponent("CameraPreview.qml");
                if (component.status == Component.Ready)
                {
                    var newObject = component.createObject(om, {"width" : test.cellWidth - 10, 
"height" : test.cellHeight - 10});
                    om.append(newObject)
                }
            }
            onClicked: createObject()
        }
        Pane
        {
            anchors.top: parent.top + 100
            width: parent.width
            height: parent.height
            id: syncTab
            GridView {
                id: test
                anchors.fill: parent
                cellWidth: width / 4
                cellHeight: height / 3
                highlight: Rectangle { width : test.cellWidth; height: test.cellHeight; 
color: "lightsteelblue"; radius: 5; }
                focus: true
                model: ObjectModel {
                    id: om
                    CameraPreview {width : test.cellWidth - 30
                        height : test.cellHeight - 30 }
                    CameraPreview {width : 10
                        height : 10 }

                }
            }

        }
    }
}

and CameraPreview.qml

import QtQuick 2.0

Rectangle
{
    color: "black"
    opacity: 0.3
}

First question: Why is highlight size is same as element size? I set highlight rectangle size as :

width : test.cellWidth; height: test.cellHeight;

and first element size is:

width : test.cellWidth - 30 height : test.cellHeight - 30

but highlight covers just element area, not all cell area

Second question:
Why dynamically added objects don't resize when i resize GridView?

var newObject = component.createObject(om, {"width" : test.cellWidth - 10, 
"height" : test.cellHeight - 10});

here new element size depends on GridView size, but it doesn't work when i resize window.

And my last question is how to change currentIndex by mouse click?