Back when I was using The Browser That Shall Not Be Named, I could see more or fewer lines in the sig depending on how I zoomed in or out (rolling the mouse wheel while holding down the CTRL key).
Oddly, sometimes making the font BIGGER would let me read more becuase the text box would expand even more than the text.
Or I think you can click on their screen name, go to their profile and read their sig block there. Or is that only their Infobox?