basplund: When you click "Key Mode" your default language is set to xx just like when you click on a flag. Since that setting is stored on the server, the next time you login you'll be in KeyMode.
The sure way to get out of it is by clicking on a flag, to change your default language again.

Because of that, whenever I need to go to key mode, I simply type in the xx at the address bar, so it doesn't get saved, since in Simple Mode the flags are invisible.