fix ZK-1891 Combobox with Validator will trigger reload selectedItem when typing,  test cases for 1891, 1895, 1899
Bug ZK-1895: Paging on listbox with onFulfill
Merge branch 'master' of github.com:zkoss/zk
Bug fixed B65-ZK-1904: Datebox doesn't sync dropdown stackup well (IE
only) http://tracker.zkoss.org/browse/ZK-1904
Merge branch 'master' of https://github.com/zkoss/zk into B65-ZK-1904
add comment for B65-ZK-1904