User-Agent: Mozilla/5.0 (Windows; Windows NT 6.1; WOW64; en-US; rv:2.0b2pre) Gecko/20100719 Minefield/4.0b2pre Build Identifier: Mozilla/5.0 (Windows; Windows NT 6.1; WOW64; en-US; rv:2.0b2pre) Gecko/20100719 Minefield/4.0b2pre I enabled DirectWrite and render-mode was set to 6. When I scroll down an up several times a page, some page areas are truncated and they are replaced by a duplication of the area above. The area can be a flash video, an image, a text area, ... This problem is recent as it is not reproducible in FF 4.0 beta 1. Graphic card : Intel GMA 4500M Graphic driver version : 8.15.10.1982 (up-to-date) WDDM model version : WDDM 1.1 DirectX version : DirectX 11 Reproducible: Sometimes

I did some new tests. From my 07/19 test, I updated : Graphic driver : 8.15.10.2181 (up-to-date for Intel, the 07/19 one was up-to-date for Acer and "Window 7 update") Flash player : 10.1.82.76 My first reference video was a video with horizontal and vertical black strips (http://www.youtube.com/watch?v=lBQkOfORlw8). My second reference video was a HD video with 2:1 format (http://www.youtube.com/watch?v=Hz86TsGx3fc) My reference image gallery was a vertical displayed HD images (http://www.pikall.com/) I scrolled up and down several times until a wrong display happened Here below is my results : FF 4.0 b1 : no problem FF 4.0 b2, b3, b4pre 20100816 : some parts of the vertical black strips of video 1 are replaced by the area above (different behavior from the 07/19 one) So most of the weird behaviors was due to an out-of-date graphic driver. It remains the video vertical black strip no refresh bug.

I added a new test with a flash video in a stand-by state (http://www.youtube.com/watch?v=lBQkOfORlw8) Here below is my updated results : FF 4.0 b1 : no problem FF 4.0 b2, b3, b4pre 20100816 : * some parts of the vertical black strips of playing video 1 are replaced by the area above, * the stand-by video has a horizontal strip that is painted with the area above

This applies to Seamonkey too (Gecko/20100907 SeaMonkey/2.1b1pre). Open http://www.urlesque.com/2010/09/09/keenan-cahill-lipsync-kid/ and scroll. OS: Win7 64 Bit pro and ult, one machine is: Phenom + AMD 790gx chipset + AMD Radeon 4890, the other is: Athlon X2 + AMD 790FX chipset + Nvidia GForce 8400GS Chipset and Video card drivers are up to date (less than two weeks old). Both machines show "bit exact" same errors, i.e. same resolution, hit F11, screenshot, compare.

Graphical Error during scroll with flash

about:config gfx.direct2d.disabled;true Does not change that error.