New filters and actions requests for Multisite admin screens

Hi
I’m currently writing a plugin that includes new functionality to the multisite part of WordPress, and I found that some actions and filters that would have been really helpful are missing.

For example, I want to add a categories to sort blogs in the network, so I would like to add an input field in the “Info” tab of the “Sites” menu, but I can’t. The only possibility is to add a field in the “Settings” tab using wpmu_update_blog_options and wpmueditblogaction actions. Why not adding the same actions in the info tab ?

Also, it would be great to have a filter that would allow to modify the $tabs array to add or remove tabs in this screen.

If needed, I can do the modification, but I don’t know the process of submitting new modifications to core. Where is the best place to look at ?

Thanks in advance