tinymce error with domain mapping

Ok here it is.

When a domain is mapped with domain mapping, image edition is no more available and returns this error (firebug)

Permission denied to access property 'tinymce'

Line 1

Config : wp 3.4.2 + buddypress 1.6.1 + domain mapping 3.0.8.3

If the domain is suppressed on a site, the image editor comes back…