firefox problem with editor on idn-domain

Hey,
I searched lots of forums for this already:
did anybody notice, that the wysiwyg-editor (I tried tinymce and mosce) does not work at all on an international domain name with firefox?
error message in popup while trying to use any funktion like "make link" or "insert image":

cannot find server on www.gr%fcnew%e4nde.de

punnycode in live-site is correct:

http://www.xn--grnewnde-4za0v.de/joomla

besides this in IE everything works fine.
of course I have newest firefox version and idn plugin.

any ideas??

[Foke]

I don´t know why people is giving thanks for the post if it has not been answered?

[qrst969]

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