ch getZclass()
1. add zk().contentWidth() and contentHeight()
2. fix flex.js issue
Feature added F70-ZK-1818: Tabbox support vertical-right,
horizontal-bottom orient,
http://tracker.zkoss.org/browse/ZK-1818
Merge branch '7.0' of https://github.com/zkoss/zk into update-tabbox
1. fixed Layout.js and Box.js for h/vflex issue
2. fixed Groupbox.js for Firefox
1. fix Listbox and Window's less file
2. fine tune some test case for ZK 7
ch close:hover style, adjust tab, scroll btn line-height and padding,
rm unused height, width prop
replace tab-hover with tab:hover, use :not() css selector instead of 
applying new style
tab background is ver-gradient now
Merge branch '7.0' of https://github.com/zkoss/zk into update-tabbox
msgbox use old img as icon now
update frozen
Merge branch '7.0' of github.com:zkoss/zk into 7.0
fine tune custom scrollbar style
Merge branch 'update-groupbox' of git://github.com/huangnoah/zk into 7.0
Merge branch 'F70-ZK-1818' of git://github.com/huangnoah/zk into 7.0
Merge branch 'update-tabbox' of git://github.com/huangnoah/zk into 7.0
Merge branch 'update-window' of git://github.com/huangnoah/zk into 7.0
1. fix V/Hflex issue
Merge branch '7.0' of github.com:zkoss/zk into 7.0