Snap! This is one of many elements of the so-called "intuitive graphic user interface" which ain't so intuitive after all.

It's not just a vision issue either; I've coached sighted computer users who had no idea what the little icons on the edges of their windows were for (close, minize, zoom, change size, elevator).

Would the outline indicators number-alpha-number-alpha-period be *usable*? Based on my out-of-date screen-reading experience, the period at the end turns the indicator into a sentence, which can facilitate navigating the reading cursor.