When configuring a connection with static key authentication, any
change to the cipher setting in the "Security" tab in the
"Advanced..." dialog are immediately discarded.  If I edit the
connection, click on "Advanced...", then on the "Security" tab, select
a different cipher, click "OK", click "Adavanced..." and "Security"
again, the cipher is already reverted to "Default".

I managed to make it work by adding the cipher key to the
configuration manually using the gconf-editor.

The same holds for any routes added in the "Routes..." dialog -- they
are discarded immediately.

Cheers,
    Sven