Imperatively setting TextEdit's alignment results in incorrectly aligned text

import QtQuick 2.5
import QtQuick.Window 2.2

Window {
    visible: true
    width: 640
    height: 480
    title: qsTr("Hello World")
    id: root

    TextEdit {
        id: textEdit

        property string t: qsTr("<b>Enter</b> some text...")

        text: t
//        placeholderText: t
        onImplicitWidthChanged: print("implicitWidth", implicitWidth)
        textFormat: TextEdit.AutoText
//        horizontalAlignment: TextEdit.AlignRight
        width: 200
        height: 200
        Rectangle {
            anchors.fill: parent
            color: "transparent"
            border.width: 1
            opacity: 0.5
        }
    }

    Timer {
        running: true
        interval: 800
        onTriggered: {
            textEdit.horizontalAlignment = TextEdit.AlignRight
        }
    }
}