Audit the .icon16 selectors in admin-menu.css

[afercia]

Noticed while investigating the admin stylesheets for color contrast, looks like the .icon16 selectors in admin-menu.css are no more used. I'm not 100% sure and I'd really appreciate some feedback though.

As far as I see, the .icon16 selectors were used only for the Welcome Panel at some point, while the admin menu always used its own selectors. It seems to me they can be safely removed.

Some history:
Introduced in WordPress 3.3 to reuse the admin menu icons on the Welcome Screen, see [19163] and [19197].

The icons were then removed with the Welcome Panel redesign for WP 3.5, see [22018] and #21368.

The selectors were still present in the MP6 stylesheets, see [26072], but no more used in any screen? If so, it would be a nice opportunity to do some cleaning.

[mmaumio]

Removed the .icon16 class from wp-admin/admin-menu.css

[isabel_brison]

The icon16 selector is no longer used in Core, but a few plugins still use it: ​https://wpdirectory.net/search/01F0APW51X955Z64064W4SQXBZ

It would be great to work out a deprecation policy for CSS so that 3rd party code can gradually move off these unused selectors.

@mmaumio : regarding your patch, the aim is to remove the CSS rules targeting icon16 altogether, not just the selector. However, we can only do that once we have come up with a way to address the deprecation issue. All the same, thanks for your effort!

[sabernhardt]

Checking for spaces and/or quotes narrows down the ​plugin directory search a bit more. A few of those matches are still not classes, and the top two plugins contain the same link.

The directory search also found ​one theme, but that's quite outdated and the icon link is not necessary when the link URLs are visible anyway.

[desrosj]

I came across this one going through open tickets missing a milestone.

Normally, I advocate for leaving code whenever there's the potential for a site to break, but I think enough time has passed and this one is acceptable to remove.

Some notes from my investigation:

• The one theme using the .icon16 class only has 50 installs. And when the relevant CSS is removed nothing actually "breaks". The icons just disappear.
• This is admin only facing, should not affect regular site visitors.
• A repeat search with ​updated results shows more matches, but fewer total active installs.
• The results show a lot of false positives and instances where plugins are using that class for something unrelated.

Moving this to the 6.1 milestone and giving a bit more time for additional thoughts to be added.

[audrasjb]

Removing close keyword :)

The patch still applies cleanly against trunk.
Considering @desrosj’s research, +1 for removing these useless CSS declarations 👍

[desrosj]

Thanks! Adding close was definitely an accident there.

[desrosj]

In 53731:

Administration: Remove unused CSS selectors related to old format menu icons.

This removes all CSS definitions related to the .icon16 class. Research shows that current ecosystem usage of this class is extremely minimal.

This selector was used for the Welcome Panel and Welcome Screen in WordPress 3.3 (see [19163] and [19197]. The icons were removed for WordPress 3.5 in [22018], but the related CSS remained, and were also included when the MP6 admin re-skinning was merged in [26072].

Props afercia, mmaumio, isabel_brison, sabernhardt, audrasjb, desrosj.
Fixes #35717.

[desrosj]

Reopening because I noticed some weirdness in Trac and Making WordPress Core after this commit. Though it's not clear how this is related just yet, as the class does not appear to be used anywhere on .org.

Tickets page 2 days ago: ​https://web.archive.org/web/20220718083419/https://make.wordpress.org/core/reports/.

Tickets page today (see screenshot, as pulled into the Tickets overlay on Trac).

[desrosj]

Reclosing. The issue above was coincidental and unrelated.