[O] Where do these backgroud colors come from?

[Detlef Steuer]

Hi!

Just updated to current git version of org:
Org-mode version 7.7 (release_7.7.674.gc609)

Running under emacs:
GNU Emacs 23.3.1 (x86_64-suse-linux-gnu, GTK+ Version 2.22.1) of 2011-10-07 on 
build40

Suddenly I have some lines with colored backgrounds, some dark
blue, some light blue  in my agenda view?! (invoked using C-c a a)

There are _no_ entries in my .emacs telling anything about colors at
all. (AFAICT.)

I like the good old white background for all my agenda lines and want it
back. What has changed in recent versions of org and how can 
those background colors be disabled?

Thx a lot
Detlef