It would be a huge usability improvement to have autocompletion of valid words. Currently, you have to type each word, and wait to see if it is rejected/removed

It would be a huge usability improvement to have autocompletion of valid words. Currently, you have to type each word, and wait to see if it is rejected/removed. Instead of waiting for each word to be typed, why not show acceptable words as you are typing, so you can tell before you finish typing if it is valid.