NPAPI plugin with a mime type ending in +xml does not correctly register in Opera.

I have a fully working Gecko NPAPI plugin written which worked before we changed our mime type for the file our plugin handles. As an example, previously the mime type was "application/blah". Since our file format is XML based and many XML formats seem to be moving to mime types like "application/blah+xml" we've made the change also. Now however, Opera dose not correctly register the plugin. On the Opera plugins page "opera:plugins", our plugin displays as:

"application/xml xml, blah, xaml"

and any time I navigate to one of our files, Opera just tries to dump out the XML and though it is just a standard XML document. Does anybody have any insight on this, or this just a bug with Opera?

I'm running Opera 9.64 on Windows 2003 32 bit.

Thanks for any input.