Version:           3.93 (using KDE Devel)
Installed from:    Compiled sources
OS:                Linux

I have a test case in http://iki.fi/eelik/bibletimehtml.html. It is output from our BibleTime program (http://www.bibletime.info).

3.93 KHTML renderer messes up the background because of this css code:
* {
        /* To work around a KDE 3.2 bug / problem */
        background-color:transparent;
}

(The comment is from our template code, I do not know what the original 3.2 problem was.)

You can see the problem when you for example resize the window or select some text. The background is not redrawn at all but old pixels remain there.

The stable (3.5.6) KHTML works fine.