I scoured the web and this forum for solution to manage categories globally, but somehow there does not seem to be a straightforward WPMU solution.
So far I have installed
"WPMU Category Defaults"
This gets me a standard list of categories in all my blogs.
Then, I installed "Sitewide extended category" widget. The problem is that this widget is not quite sitewide, it only gets posts from one blog.
I think that the wpmudev "List-All-Recent-Post-By-Category-Filter"
(http://wpmudev.org/project/post-from-all-blogs-category-filter) might be just what I need, as I don't want to resort to yet another aggregation table. Problem is when I install the plugin "List-All-Recent-Post-By-Category-Filter", I get the code ouputed in my header instead of just having the functions available.
I searched my index and header files but can't seem to find the cause.
Could you please let me know if you have been able to install and use the "List-All-Recent-Post-By-Category-Filter" plugin without error?