bug fixed: ZK-909 the second errorbox should not drag when click close
bug fixed: cant assign negative number to height/width in ie8
style fixed: the close btn of errorbox should not apply opacity in ie8
style fixed: the style error make size problem in ie8
minor fix: replace " with ' in Timbox.js
bug fixed B36-2678340: click btn-up icon first, then click btn-up btn,
the value should not be null.
Merge branch '7.0' of https://github.com/zkoss/zk into fix-ie8