Browsing some source on GitHub, I noticed that when I paged down to certain points the GitHub header and footer would repeat over the page content.

Graphics -------- Adapter Description: NVIDIA Quadro K600 Adapter Drivers: nvd3dumx,nvwgf2umx,nvwgf2umx,nvwgf2umx nvd3dum,nvwgf2um,nvwgf2um,nvwgf2um Adapter RAM: 1024 Asynchronous Pan/Zoom: wheel input enabled ClearType Parameters: Gamma: 1800 Pixel Structure: R ClearType Level: 100 Enhanced Contrast: 50 Device ID: 0x0ffa Direct2D Enabled: true DirectWrite Enabled: true (10.0.10240.16430) Driver Date: 7-22-2015 Driver Version: 10.18.13.5362 GPU #2 Active: false GPU Accelerated Windows: 2/2 Direct3D 11 (OMTC) Subsys ID: 094b10de Supports Hardware H264 Decoding: Yes Vendor ID: 0x10de WebGL Renderer: Google Inc. -- ANGLE (NVIDIA Quadro K600 Direct3D11 vs_5_0 ps_5_0) windowLayerManagerRemote: true AzureCanvasBackend: direct2d 1.1 AzureContentBackend: direct2d 1.1 AzureFallbackCanvasBackend: cairo AzureSkiaAccelerated: 0

I'm on the latest Windows Nightly build from yesterday (2015-10-29).

Does the problem go away if you disable the pref layers.async-pan-zoom.enabled (requires restart)?

Yes, toggling that pref makes it go away. I also figured out my actual STR: 1) Load that URL 2) Scroll down with the mouse wheel for a bit It doesn't reproduce scrolling with the keyboard only. Once the graphical glitch is rendered, however, I can scroll with the keyboard and it persists.

The file got moved in the repo, so updating URL. However I can't seem to repro the issue on my OS X nightly. I'll try on Windows.

When I try this on Windows with Direct2D, we assert immediately. The displayport is clamped to the maximum texture size (16k), but scrollbars ignore the displayport. In this case the scrollbars are ~135,000 pixels high, so we fail to allocate a new frontbuffer. This is probably bug 1214261. (Assigning to re-test this after that bug is fixed.)

I think this is the same bug as bug 1225868. The screenshot looks very similar to it. :ted can you try and see if the bug is correlated with a page zoom like bug 1225868 is?

(In reply to Benoit Girard (:BenWa) from comment #7) > I think this is the same bug as bug 1225868. The screenshot looks very > similar to it. > > :ted can you try and see if the bug is correlated with a page zoom like bug > 1225868 is? See comment #6, I'm fairly certain this is bug 1214261. Disabling the assert or using an opt build repros the problem, and clamping scrollbars to the displayport makes it go away.

It could be that bug 1225868 is also a scrollbar issue - it's true that the screenshot here looks very similar to what :jdm was seeing.

Right. I saw comment 6 which I don't disagree with. Like Kats said perhaps these bugs could all be related. In any case if we fix one we should check the others.

Please retest on the Jan 11 nightly; this should be fixed now that bug 1214261 has landed.

This doesn't reproduce for me anymore. Thanks! (Sorry I never answered the NI here...)