In addition of this ticket : http://tracker.zkoss.org/browse/ZK-2810
The fix won't work when using an include and append dynamicly components.

Fiddle : http://zkfiddle.org/sample/2r3n2ub/1-tabbox-include

Left one : never good.
Center one => correct.
Right one => only good when switching tabs after appending(fix of Robert in switching tabs)