Nikola Plejic wrote: > def handler(**kw): > a = txt.text > b = txt2.text > a = int(a) > b = int(b) > lbl.text = a + b lbl.text = str(a + b) Unlike other languages Python does not automatically change the type for you. You will grow to appreciate this, as it can lead to some very subtle bugs that can be hard to catch later on. regards Max M