Since a bunch of KDe devs are probably reading here, there's a little thing I'll try to bring to your notice.
I'm strictly unable to describe the bug technically, and I'm not so good at leaving bug reports anyway. They tend to get closed quickly, no matter how real the bug could be, there's always something that is requested that I'm unable to feedback.
You can visit this page:
http://www.contrees-du-reve.com/
You will see that on the right column, there are some google ads (=javascript), which are supposed to be partly covered by a fixed div (the footer which does not scroll). However, the javascript content tends to flash back and forth over the fixed footer when you scroll the page. And when you stop scrolling down, the stripe of the google ad area which was initially covered by the footer does not display.
At least that's how it renders for me in konqueror. Hope you can see it yourself.
As far as other browsers go, IE7-8 and Opera render this correctly. Firefox also has it right, but very awfully slow.