TextEdit cursor doesn't always adapt to text format

import QtQuick 2.6
import QtQuick.Window 2.0

Window {
    visible: true
    width: 200
    height: 200

    Shortcut {
        sequence: "Ctrl+Q"
        onActivated: Qt.quit()
    }

    TextEdit {
        text: "<span style=\"font-size:20pt;\">Blah</span><br>blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah"
        textFormat: TextEdit.RichText
        cursorDelegate: Rectangle { color: "red"; width: 2 }
    }
}