Merge pull request #6 from huangnoah/6.5

6.5
Merge branch 'master' of https://github.com/huangnoah/zk
Merge branch 'master' of https://github.com/zkoss/zk
fix zul and add test case
fixed IE6's JS error
Bug ZK-2264: After change to the next page, we cannot scroll a frozen grid horizontally
Merge branch 'master' of github.com:zkoss/zk
Enables registering concrete richlets instead of their class names

In that case, the ZK will get the concrete class and it does not have to
construct the new instance.

So, we'd be able to set the richlet's properties before registering it
to the ZK. Now, we have to set all properties in the richlet's
constructor what is not adequate in some cases.
fixed the scrollbar issue for Mac's safari for B50-3354057.zul, B50-3357475.zul, B50-ZK-241.zul, B50-ZK-309.zul, and B50-ZK-489.zul
fixed IE 6 issue for Groupbox's test cases. (like B50-3356022.zul)
Merge remote-tracking branch 'upstream/6.5'
Bug ZK-2267: Popup is only sometimes "visible" when it is opened
Merge remote-tracking branch 'upstream/6.5'
Bug ZK-2269: Comet Server Push send infinitely request if using Apache as proxy server
Merge branch 'richlet' of https://github.com/mkrizmanic/zk
fine tune
Bug ZK-2262: JS error showed after moving movable panel
    - A side-effect caused by this commit - https://github.com/zkoss/zk/commit/96c3894453ac1c5fa6898a527abd4d5657a7570e
add testcase in config.properties
Merge branch '6.5' of https://github.com/zkoss/zk into 6.5
Merge branch '6.5'