Fun side effect of long-running AJAX apps: even though Google disabled the feature, it will still be live for everyone who has a gmail window since (at least) y

Fun side effect of long-running AJAX apps: even though Google disabled the feature, it will still be live for everyone who has a gmail window since (at least) yesterday. The feature must have had a timed activation. You have to refresh the page. And apparently even that may not be enough. I Ctrl-R refreshed in Firefox and still saw the button (aggressive caching?). I closed the tab and loaded gmail in a new tab, and finally button went away.