(I don't know the category under which this bug should be filed. I simply assume xorg, server/general is OK.)
I updated from xorg-server 1.9.5 to 22.214.171.1241. As a result, new windows or dialogs have "pixel garbage" in them when they first appear. This results in menus that pop-in (like context menus, pop-up menus, selection lists, etc) that are supposed to fade-in in my desktop (KDE 4.6.1) looking broken. For example, when I right-click in Firefox or click on a pop-up list, the "pixel garbage" appears immediately, and only then is a fade-in performed that gradually replaces the garbage with the actual widget.
This does not happen with 1.9.5. My system:
Gentoo Linux AMD64, kernel 126.96.36.199, radeon DRM with KMS enabled, xf86-video-ati Git master, mesa Git master using Gallium, KDE 4.6.1 with Desktop Effects enabled. The graphics card is a Radeon HD4870.
Sounds like bug 34427.
And indeed it is a duplicate :-)
*** This bug has been marked as a duplicate of bug 34427 ***