Background transparency QQuickWindow with QML boxes on iOS

[Francky033]

Hello,

On Windows, Linux, Android and macOS with Qt 5.15.5, I can display transparency in qml boxes using the command

QQuickWindow::setDefaultAlphaBuffer(true);

However, it doesn't work on ios... I always get a black background...

Did I forget something?

Thanks to all of you !

    ```
    engine_configuration->rootContext()->setContextProperty("anchormenuandroid", anchor_menu_iosQML);

component_menu_iosQML = new QQmlComponent(engine_configuration);

component_menu_iosQML->loadUrl(QUrl("qrc:///qml/menu_android.qml"));

if (component_menu_iosQML->isReady())
{
       menuiosQML = qobject_cast<QQuickWindow*>(component_menu_iosQML->create());
	
       menuiosQML->setWidth(300);
       menuiosQML->setHeight(200);
       menuiosQML->setPosition(500, 600);

       menuiosQML->setFlags(Qt::WindowStaysOnTopHint | Qt::FramelessWindowHint | Qt::Tool);
	
       menuiosQML->showNormal();
  }

// qml

import QtQuick 2.15
import QtQuick.Window 2.15
import QtQuick.Controls 2.15
import QtQuick.Controls.Material 2.15
import MyLib 1.0

Window {
    id: main

    property double coef: anchor.Coef
    property int timeoutInterval: 50
    signal timeout

    modality: Qt.NonModal

    color: "#00000000"
    opacity: 1.0
    x: 0
    y: 0
    width: 200

    height: 200

    visible: true

    Flickable {
        id: flickableMain
        anchors.rightMargin: 0
        anchors.leftMargin: 0
        anchors.topMargin: 0
        anchors.bottomMargin: 0
        anchors.fill: parent
        boundsBehavior: Flickable.StopAtBounds

        contentWidth: parent.width
        contentHeight: h > 1000 ? h : 1000

        focus: true

        Keys.onUpPressed: scrollBar.decrease()
        Keys.onDownPressed: scrollBar.increase()
        Keys.onPressed: {
            if (event.key === Qt.Key_Back) {
                anchor.sendMouse(-700)
            }
        }

        MouseArea {
            anchors.fill: parent

            onMouseXChanged: {
                anchor.sendMouse(mouseX)
            }

            onReleased: {
                anchor.sendMouse(-500)
            }

            onPressAndHold: {
                anchor.sendMouse(mouseX)
            }
        }

        Column {
            id: column1
            anchors.left: parent.left
            anchors.right: parent.right
            anchors.top: parent.top
            anchors.rightMargin: 20
            anchors.leftMargin: 10
            anchors.topMargin: 40
            anchors.bottomMargin: 20

            antialiasing: true
            spacing: 30

            x: 0

            width: parent.width
            height: 950

            Rectangle {

....