if some frequency is under regulatory constraints its not shown in the
Gui. These frequencies are marked by a "*" after the frequency.
-> The ifconfig manpage has some more explanation.
$ /sbin/ifconfig ath0 list chan
Channel 11 : 2462 Mhz 11g
Channel 12 : 2467* Mhz 11g
The function wireless_get_channellist($if) in interfaces_wlan.inc should
process this information.
Removing all "*" helps but seems ugly ;)