TextField {
    id:textField
    text:"11:11:11"
    width:200
    height:80
    font.pointSize: 15
    color:"white"
    inputMask: "99:99:99"
    validator: RegExpValidator { regExp: /^([0-1s]?[0-9s]|2[0-3s]):([0-5s][0-9s]):([0-5s][0-9s])$ / }
    horizontalAlignment: Text.AlignHCenter
    verticalAlignment: Text.AlignVCenter
    inputMethodHints: Qt.ImhDigitsOnly
}

TextField {
    ..
    Keys.onBackPressed: text = "00:00:00"
}

TextField {
    ..
    Keys.onBackPressed: {
        var index = cursorPosition
        var char = text.charAt(index)
        if(char != ":"){
            text = text.substr(0, index) + "0"+ text.substr(index);
        }

    }
}