Thanks --- VERY happy ---- All I had to do is, AFTER choosing to "ADD TO OPERA" from the Chrome Webstore, to go to the extensions page, (which opened automatically), and click install, (again, AFTER saying install from the Chrome page). Great extension -- However, BOTH the backspace AND this "ADD FROM CHROME WEBSTORE" extension should be built into Opera.
Now, backspace works in ALL my browsers--AGAIN!