Comment 6 for bug 237562

Actually, the problem DOES occur with the stock Nautilus patterns as well - make the window size SMALLER than the dimensions of the stock background tile image, close and re-open the Nautilus window and you will see the rendering issue. I noted this on my EeePC701 with its diminutive screen dimensions when I resized a window small enough to only fit in two icons, closed it, reopened it and then scrolled.

The black (or corrupted) areas of the background you will observe match the dimensions of the background image exactly, ie: a background 1024x768 in size inside a Nautilus window 640x480 in size will have black/corruption from pixel 641 through to 1024 horizontally and pixel 481 to 768 vertically. When the background wraps, it will render correctly, but again only to the original 640x480 dimensions of the window where it will black/corrupt again.

Make the window larger, then close it and re-open it and the black/corruption is gone (simply because the background image dimensions are smaller than that of the window, so it therefore tiles properly now).

I've observed this in Ubuntu 9.04 and 9.10. The black appears in Virtualbox and Intel gfx adapters and full-on corrupted/copied chunks of video memory appear in place of the black when using NVidia gfx adapters.