What are the blinky black lines?

[celebrian23]

When I open a webpage, I see these black lines. Sometimes they blink, sometimes they don't. And not on every page, but sometimes during my internet session it will happen. At first I thought they were cursor thingys when you type, but they're in places I can't type. What are they and why are they there?

[iMeowbot]

Is it possible to get a screen shot of these lines? Are the any pages where you see them consistently? If they don't show up in screen shot, could you maybe give some specific examples of where you see them? Oh, and your favorite web site isn't random-blinking-black-lines.net, is it?

[celebrian23]

next time they appear I'll try to screenshot them (they come up a lot on MR but it's seeminly random). If it helps, I use firefox

[celebrian23]

what are the black lines there for?

[emw]

Can't say I've ever seen them. Again, a screen grab would be helpful.

Are they like cursor lines (vertical) or are they horizontal? How big? All websites, or only some? Only in Firefox?

[celebrian23]

Okay they're vertical. Sometimes they blink, but it's more common for them not to. Sometimes it's one line, sometimes, like in this shot, there's a few.

[celebrian23]

i only use firefox, I've only used opera and safari for really limited amounts of time

[szark]

Do they always appear when you're loading another tab in the background?

[JBot]

do the lines follow the browser in the same area of the window if you were to drag the browser around the screen?

Do they appear while using any other application, or just with the web browser?

[celebrian23]

Do they always appear when you're loading another tab in the background?
-Not sure. I'll check next time I seen them

o the lines follow the browser in the same area of the window if you were to drag the browser around the screen?
-will check

Do they appear while using any other application, or just with the web browser?
-only web browser

they also disappear if i zoom down then back up tol where they were (but won't disappear if I just watch them even for more than 5 minutes)

[celebrian23]

Update to questions:

Do they always appear when you're loading another tab in the background?
-no, it doesn't matter if another tab is loading or not

do the lines follow the browser in the same area of the window if you were to drag the browser around the screen?

Yes they do