Little black rectangles when scrolling up?
I know this has been reported before, but none of the previous "fixes" solve it for me and I hope I can provide more information. Much like the description says, when scrolling windows up (only up) I get little black rectangles approximately 5 x 10 pixels scattered across the bottom portion of the screen. The "speckles" dissappear as they are scrolled up the visible portion of the page. Typically they are all gone by the time they reach 1/3 of the way up.
They don't happen all of the time; nor on all web sites. Typically, sites that are text heavy are worse than those with lots of images and other media. Enabling and disabling hardware accelaration has no discernable effect. Turning off smooth scrolling seems to eliminate the problem.
The speckles are not completely random. They only ever occur in "odd" (depending on how you index them) columns. If I scroll up and down repeatedly by small amounts. I start to build little black columns of speckles.
Some screenshots: Typical: http://imgur.com/UVtq0HD Extreme: http://imgur.com/VVJaHZo
I am using the Intel opensource drivers, which seems to be a common thread on this problem.
Oddly enough, having a tab open that has a text entry box seems to eliminate the problem in all tabs. for instance, I can not make it hapen while I am filling in this report, in this or any other tab.
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Some furthur observations: Any action which causes a screen redraw makes the speckles dissappear: resizing the window, moving the window, even just clicking on the window header bar. The problem is worse with larger windows than smaller windows. My destop is 1920x1080, a full size window (1920x1080) or large window (~1500x900) is much more prone to displaying the issue than one at ~600x800.
The problem is not restricted to Firefox. Other applications using the Seamonkey rendering engine seem to be affected. I get the same issue in Thunderbird, though not as noticable and much harder to capture. (Every time I switch focus away from the Thunderbird widow to take a screenshot, it refreshes. :/)
Try to increase the value of the general.smoothScroll.mouseWheel.durationMaxMS pref on the about:config page a higher value like 1000 to see if that makes a difference with smooth scrolling enabled.
Thanks for the suggestion.
No. Setting that to 1000 doesn't eliminate the problem. It certinly makes scrolling more sluggish feeling, but scrolling at low speeds result in things like this: (screenshot) http://imgur.com/W5TfJ1y
As an aside, my observation about text entry boxes on the page making it not happen was wrong. See the above image.
[bleh. fixed typos]
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