I used to be able to scroll the mouse over a post teaser and view the entire question. Recently, I seem to have lost that ability. So, (a) is this a change at the SD or just me? And, (b) if me, how do I get it back??? 
I suspect it is a browser issue for you, as nothing has changed that I know of on the board and I still see the little yellow boxes when I mouse over threads.
See thread below re"annoying pop-ups."
Hope this helps.