I have just downloaded FF4 and so far I'm liking it a lot - it seems to be speedier than my previous version of FF.
As I type in the "quick reply" box, I am seeing two white, vertical white lines briefly appearing as I hit the keys/space-bar (or left click). Bit puzzled about that... anyone else notice it happening? I can't get a screen shot to illustrate... ooh, yes I can!! Will attach it below, you can just make out the tiny lines dissecting the black part of the surrounding box, if you look (very) closely.
(They are still happening in the "go advanced" reply area too. It's no biggie, I'm just a bit intrigued.)
At the same time, I downloaded the
Flagfox extension, which
"Displays a country flag depicting the location of the current website's server and provides a multitude of tools such as site safety checks, whois translation, similar sites, validation, URL shortening and more..." Hmm... might be interesting. Don't think it is the cause of the "lines" though, because they happened before I got the extension.