zhouli ,

I hope you will read this (I will send you an email in a few min.).

Right now,
border-radius-clipping.html test
has several issues:

• border-radius-clipping.html is currently failed by all browsers
• in the test, there is in fact 2 sub-tests
• the #dummy related sub-test generates horizontal and vertical scroll bars which are not present in the reference file
• the tiny blue border is not the target of the test itself (and not part of the test itself) but, once curved, it can generate differences detected by screen shot comparison
• the assert text says should clip but it must say must clip instead
• a meta charset is missing in the test

I propose
http://www.gtalbot.org/BrowserBugsSection/CSS3Backgrounds/border-radius-clipping-GT.html
and
http://www.gtalbot.org/BrowserBugsSection/CSS3Backgrounds/border-radius-clipping-002-GT.html
to rehabilitate your current test with these 2 replacement tests.
The correspondent reference files are:
http://www.gtalbot.org/BrowserBugsSection/CSS3Backgrounds/reference/border-radius-clipping-ref.html
and
http://www.gtalbot.org/BrowserBugsSection/CSS3Backgrounds/reference/ref-nothing-below.xht

zhouli, if you read this, I propose we co-author these 2 new tests and replace your current test.