Sometimes, when resizing a div with round corners using javascript, glitches can be see along the div's border. See my online demo. The bug is hard to reproduce, but my demo does. If the resize goes fast, there no glitch. In my case, the content used to force de div to rezise comes from an "ajax" request and an image locate on another server. If you select the page content, the glitch dissapear. Look like a refresh issue.
Created attachment 10847 [details] resize glitch
Created attachment 10848 [details] Some more glitches
Created attachment 10849 [details] Reduction Bug 6301 was similar to this, and I think you can improve the fix for that bug to cover this bug as well.
*** This bug has been marked as a duplicate of 10699 ***