ZK 7 has made some changes to its API. Also, changing box-sizing to border-box may break layout due to wrong size calculation.

For example, the following changes would make pivottable unusable in ZK 7.
1. JSONArray.toJSONString(List) has been replaced by JSONArray.toJSONString(Collection) in ZK 7.
2. Window#setMode() throws InterruptedException in ZK 5.0.11, but the throws clause is removed in commit 04820db...

This feature allows pivottable component to be used regardless of the underlying ZK version, starting from ZK5.