In the upper right hand corner of the TB screen. Used to be able to click on it and a small dialog would open allowing you to click on the alert or click elsewhere to ignore. Now, no more dialog -- you are taken to your Alerts url and must cycle back to the home page. I noticed this oddity a few weeks ago in Safari and thought it must just be Safari and someone would notice and fix it. But I just had it happen in Chrome too, although not consistently. Anyone? Bueller?