Links widget does not display links if no Link Categories exist.

[mfields]

Here are the steps I used to detect this running on the latest trunk:

1. Ensure that the 'link_manager_enabled' option has a value of "1".
2. Ensure that no Link Categories exist (default behaviour after Step 1).
3. Add a single link via Links -> Add New.
4. Create an instance of the Links widget in the sidebar.
5. View your site.

At this stage, the Links widget should not display.

I believe that this problem exists because there is no default link category. The dropdown element in the widget's UI labeled "Select Link Category" can only be set to "All links". When this happens, ​the query in wp_list_bookmarks() returns no results. Prior to 3.5 there has always been a "Blogroll" Link Category which appears to have worked much like the default posts category. I think that the absence of a default Link Category may be part of the problem here.

[MikeHansenMe]

Here is a start.

[bpetty]

Even though this appears to have been a problem in 3.4 and older, it's still basically a regression because of the change in default link categories (not having them anymore). I'd bump priority, but it's also still only a problem for anyone re-enabling the link manager, which should be very few.

This should still be addressed for 3.5 though. I've tested the patch and it works.

[nacin]

In 22426:

Display links if no link categories exist. props MikeHansenMe. fixes #22216.

[ryan]

This breaks the links widget. categorize is stomped.

[ryan]

Tested with link categories and with all link categories deleted. Categorized for the former, one list for the latter.

[nacin]

[22910] missed the ticket.