How to center text in QML combobox

Hi,

I have the following code:

Code:

---

Window {
    id: window
    visible: true
    width: 640
    height: 480
    title: qsTr("Hello World")
 
    GroupBox {
        id: groupBox
        width: label1.width + comboBox.width + label2.width +25
 
        height: comboBox.height * 3 + 25
        font.pointSize: 14
        anchors.horizontalCenter: parent.horizontalCenter
        anchors.verticalCenter: parent.verticalCenter
        title: qsTr("DDM")
 
        Label {
            id: label
            text: qsTr("Limits centered on")
            anchors.rightMargin: 5
            anchors.right: comboBox.left
            anchors.verticalCenter: comboBox.verticalCenter
        }
 
        SpinBox {
            id: spinBox
            width: 200
            editable: true
            value: 100
            to: 200
            anchors.top: comboBox.bottom
            anchors.topMargin: 5
            anchors.left: comboBox.left
        }
 
        ComboBox {
            id: comboBox
            x: label1.width
            width: 200
            font.pointSize: 14
            model: ["DDM 0", "Mean value"]
            delegate: ItemDelegate {
                contentItem: Text {
                    font.pixelSize: 22
                    text: modelData
                    horizontalAlignment: Text.horizontalCenter
                }
            }
        }
 
        Label {
            id: label1
            text: qsTr("Reduced ICAO limits")
            anchors.rightMargin: 5
            anchors.right: spinBox.left
            anchors.verticalCenter: spinBox.verticalCenter
        }
 
        Label {
            id: label2
            text: qsTr("%")
            anchors.leftMargin: 5
            anchors.left: spinBox.right
            anchors.verticalCenter: spinBox.verticalCenter
 
        }
    }
}

---

I would like to center the text. How can I do?
A secondary question is:
I have set in the combobox font.pointSize: 14
Bust I have to set font.pointSize: 22 in the delegate to get the same size of the text. Why?

Thank you