var isLoaded = false;
    var theComboString = new wijmo.input.ComboBox('#theComboString', {
        selectedIndexChanged: (sender) => {
            if (isLoaded) {
               console.log('user selection')
            }
        },
        isDroppedDownChanged:()=>{
            isLoaded=true;
        },
        itemsSource: getCountries()
    });