ALTGr doesn't work in 13.10

[marwell]

Since I upgraded to Kubuntu 13.10 my ALTGr key doesn't work anymore. I can 
not input third and forth level characters. 

In system settings the ALTGr key is set to 3rd level input, but it doesn't 
work. I checked xbblayout and the us definition is including the old (13.04) 
definitions on 3rd and 4th level. 

Something changed from version 13.04 to 13.10., I found more people on 
forums discussing the problem. Anybody any idea? Any help very much 
appreciated. Thanks!