User-agent: Mozilla Thunderbird 1.0.2 (Windows/20050317)
It obviously not clear. The feature "branding" plugin is a plugin that
is used to "brand" the feature (ie icon, name etc in the about ). This
is not product branding which also can add content to the about for the
"product". The only way to get content loaded at runtime is via a plugin
(so you can use fragments for localization etc). So for features to show
up in the about dialog they need a plugin to host that information.
I normally just create a plugin with the same id as the feature which by
default becomes the branding plugin for that feature. But if you don't
want to do that you can put the feature branding information in a plugin
with a different id and then use the "plugin=" attribute of the feature.