I think that you are using a old firefox versión (mine 17) that don't support websocket:
http://jimbergman.net/websocket-web-browser-test/
I have fixed the dialog Spanish translation (will be online in some days). I close this issue.
I think is supported since version 11:
https://developer.mozilla.org/en-US/docs/WebSockets#AutoCompatibilityTable
Hello I am a Debian testing user and I use Fireefox which is named Iceweasel in Debian.
The version shipped in testing is 10.0.5 as of today.
When I try to open Kune it says that my browser is not supported.
Maybe is just because the name is different (Iceweasel instead of Firefox)? Version 10 is not so old...
Thanks
Steps to reproduce:
Open http://kune.cc with Iceweasel 10.