1. import war file into eclipse.
2. run jetty on this project.
3. open browser and go to localhsot:8080/zss.test/
(depends on your enviroment)
4. click "10-chart.zul".
5. zss got stuck with loading screen.

extra information:
this issue could be occurred at js dependency loading parts in zk core.
you can see another page owning "chart" or "picture" keyword, it has the same issue.
but if you load any other pages, then insert a chart or picture after that, the operation will work perfectly.