Qt 5.9 > Qt Quick Controls 2 > ComboBox: the textbox doesn't support multiline text because it ignores formatting

[Konst_777]

QML Type ComboBox in version Qt 5.9 behaves differently from Qt 5.8. In Qt 5.9 the textbox of a ComboBox ignores formatting and doesn't support multiline text and HTML.

Here's a minimalistic example for producing the problem:
main.qml:

import QtQuick 2.8
import QtQuick.Controls 2.1
import QtQuick.Window 2.2

ApplicationWindow  {
    visible: true
    width: 400
    height: 300
    title: qsTr("ComboBox test with Qt 5.9")

    ComboBox {
        id: multilineComboBox
        anchors {
            topMargin: 20
            rightMargin: 20
            leftMargin: 20
            top: parent.top
            right: parent.right
            left: parent.left
        }

        model: [
            "multiline:\n choise 1",
            "multiline:\n choise 2",
            "multiline:\n choise 3"
        ]
    }
}

The result for Qt 5.8:

The result for Qt 5.9:

Is it possible to fix this problem in the next version of Qt 5.9?

[raven-worx]

@Konst_777
Is it the exact same QML file tested with both versions? If so it is a regression bug and should be reported (if not done already).

[Konst_777]

Yes, it is the exact same QML file except line "title: qsTr("ComboBox test with Qt 5.9")", where the version number of the Qt was changed from "5.8" to "5.9".
Accordingly to your advice I reported about this problem in QTBUG-62686.