With the current devel snapshot I get an js error with Firefox, Opera and IE when I am not logged in:
Error: SIG is not defined
Source File: http://horst/dokuwiki/lib/exe/js.php?edit=1&write=1
Error: [Exception... "'Error: No menu commaner found for URL: http://horst/dokuwiki/doku.php'
; when calling method: [nsIDOMEventListener::handleEvent]" nsresult: "0x8057001c (NS_ERROR_XPC_JS_THREW_JS_OBJECT)" location: "<unknown>" data: no]
Presumably, this is connected with the fact that the signature button shows up when not logged in while it shouldn't.
Hence, this error does not occur while being logged in.