Merge branch 'B70-ZK-1807' of git://github.com/danchen0720/zk
Bug refix ZK-2061: the merge error causes vision test fail
Change tree's check icon to image in IE8
Bug fixed B70-ZK-2070: grid onScroll client-side event not working in 7.0 http://tracker.zkoss.org/browse/ZK-2070