While diagnosing a problem users have with some sites, I have found that the console reports the same type of error.
Test sites :
(select NHL score)
the slideshow is not visible in KM, but is in Mozilla.
uncaught exception: [Exception... "Cannot find interface information for parameter arg 0 [nsIDOMWindowInternal.controllers]" ...
In the js code on these pages
the detectBrowser function has this:
In the urlbar type
in Mfcembed (installed in Mozilla dir), this text appear in the window:
in KM nothing appears, but the console shows an error message.
I'll try more tests and report here.