I've been having visual problems with my notification bubbles, their background colour changed from dark grey to grey permanently after installing gnome 3 and using How can I reset my GRUB background to default? for restoring the grub background. Unfortunately I wasn't careful, and didn't read the article through, and either purged the desktop-base or removed the desktop-grub.png.
My real problem is, that after installing then using NotifyOSD Configuration, changing the background colour from dark grey (NotifyOSD settings were still set on that) to black didn't have any affect on the background colour of the bubbles.
I'm using Ubuntu 12.04.
Thank U for all the answers!