- do you have any add-ons/extensions? You didn't say.
- do you use a user.js or userChrome.css? You didn't say.
- are we talking about 'everything' - message pane, opened message in
a tab or window, editing reply message, all, less?
Here are some articles about tweaking/ changing the default/ in other
ways than display config.
http://kb.mozillazine.org/Pane_background_colors You can change the
background colors in Thunderbird's (or Mozilla Suite's) preview pane,
folders pane, and message list pane, etc. by modifying your user.js and
userChrome.css files as described below.
http://eriwen.com/css/tweaking-thunderbirds-chrome/ Personalize your
Thunderbird by changing it’s chrome <beware the feral apostrophe in the
article's title>
http://kb.mozillazine.org/White_on_black_-_Thunderbird This page
contains an example of how to use your userContent.css file to display
messages in Thunderbird in white text on a black background.
about:config
http://kb.mozillazine.org/Mail_and_news_settings
msgcompose.background_color
--
Mike Easter