Support custom `theme action links` again

[georgestephanis]

With THX38 merging into core, the theme_action_links filter got dropped so it's no longer possible to add custom links to themes.

Let's restore that functionality.

For an example of how this would be used:

​https://github.com/georgestephanis/theme-downloader/commit/bb8584add9cf0039580902632e30652829798f52

[helen]

Boo, dropped filter. Why not keep the name the same?

[JohnPBloch]

+1

Had to add a workaround in ​Child Themify to deal with this issue. It was ​distinctly not pretty.

[JohnPBloch]

Replying to helen:

Boo, dropped filter. Why not keep the name the same?

Because it wouldn't be doing the same thing, I suppose. Links need to be updated to work with the backbone templating since they only get printed once and have theme-specific data added later by the render() method.

[georgestephanis]

what he said.

You can see both implementations here:

​https://github.com/georgestephanis/theme-downloader/blob/master/theme-downloader.php

(my implemention assumes the above patch)

In the old way, it was just a case of shoving the link into an array and wp_list_table would take care of the output.

The new way, you actually need to modify the backbone template to expect it and prepare a place, in addition to adding the link to the $theme object that's output in the js.

I also discussed this with @matveb here: ​https://twitter.com/daljo628/status/426835088278437888

[helen]

I think this poses kind of an interesting general question - how do PHP hooks mix with JS templates?

Upon further thought (10 months of thought, apparently), I think this particular action isn't one I'd be excited to support. The current UI doesn't scale to fit arbitrary things in that spot and, as above, I think this is perhaps more of an opportunity to think about the bigger picture.

[obenland]

Replying to helen:

The current UI doesn't scale to fit arbitrary things in that spot […]

Exactly that was my first thought too, when I read the summary of this ticket.

I agree, let's not continue to support that.