This may be a bug or this may be intentional, but in the current 3.1alpha the code pane in browsers no longer makes the selector appear bold.  It looks like the change was introduced in update #4055, with the code pane consolidation changes... the relevant code is in Browser>>selectedMessage.

If the change was intentional, I guess I'd say that I've gotten used to it being bold and kind of prefer it that way... also, it was sort of a convention that versions browsers would not make the selector bold, but "live" browsers would, so you'd know whether you were looking at a method in the image.  (On the other hand, I guess FileContentsBrowsers didn't follow this convention... so perhaps it's not a big deal.)

- Doug Way
  dway at riskmetrics.com