QOOXDOO: Workaround for error: "Could not set the model selection. Maybe your models are not unique?" when removing all items in an array?

Question

I get this error when I try to remove all the elements in the array, which is the model for the selection Box. From what I understand this happens because I have the first row selected and I remove all items, in order to replace them again. The how should I do this to work?

// is only created the first time
weeks: new qx.data.Array()

// every time I change the year I have to
weeks.deleteAll();
// for each week in the year add the week
weeks.push(qx.data.marshal.Json.createModel({
     label: "week: " + weeksNum
    ,fromDay: week.startDay
    ,toDay: week.endDay
}));


// the view
var weeksSelectBox = new qx.ui.form.SelectBox();
var weeksController = new qx.data.controller.List(this.__headerData.weeks, weeksSelectBox, 'label');
content.add(weeksSelectBox);
weeksSelectBox.addListener("changeSelection", function(e) {
    var selectedItem = e.getData()[0];
    var model = null;
    if(selectedItem){
        model = selectedItem.getModel()
    }
    this.__component.onWeekSelected(model);
}.bind(this));