Merge pull request #94 from jerrywell/6.5

refix ZK-2294: Combobox popup scroll back to top when navigating by k…
add zul test file for ZK-2285
Bug ZK-2379: selectbox with model error when calling parent invalidate()
Merge branch '6.5' of github.com:zkoss/zk into 6.5
refix B65-ZK-2379 for ZK Bind issue
Fine tune for B65-ZK-2379
Bug ZK-2389: Append popup component to Hlayout throws JavaScript error