ClassCastException when decrease indent cell with zk 9.6.0.2

[hieplq]

1. clone source at 5.0.0.1 (master at moment)
2. open pom.xml change zk.version to 9.6.0.2
3. run "mvn jetty:run"
4. open http://localhost:8080/keikai-app-oss/
5. input something to cell
6. make sure font is calibri and size = 11
7. click decrease indent happen ClassCastException with message "class java.lang.Double cannot be cast to class java.lang.Integer"