You tell it which dictionary to use (as in UK or US...etc.) and it beeps and YOU click a btter (arrghh..."click*)better word that it suggests..or not. It changes the word instantly.
If I am typing anything long, I can put a 'box' right above this area so I don't even have to look at the tray.
Best thing since sliced bread! (unless you like to slice your own bread)