Sybre Waaijer

Hover Highlights is a simple WordPress plugin that adds a subtle highlight effect to the Gutenberg/Block Editor. When you hover over a block, it gets highlighted with a dashed outline and a box-shadow. The highlight disappears when you focus on the block to reduce distraction.
This plugin is ideal for content creators who want to visually distinguish individual blocks within the Block Editor.
The code and this readme are mostly written by ChatGPT.

Hover Highlights – Editor highlighting

Adds highlighting on hover with a distraction-free experience for the Gutenberg/Block Editor.

jesucarr

The main reason for the development of this plugin was the lack of options supporting the HTML5 recommendation, where the code snippets should be tagged with <code>pre</code> followed by <code>code</code>, and optionally a class starting with <code>language-</code> and then our language.
You can use the plugin like this:
<pre><code><pre class="prettyprint"><code class="language-php">
// my code
</code></pre>
</code></pre>
Also very important is that although this plugin loads different files depending on your configuration, it fully supports caching scripts (<a href="https://wordpress.org/extend/plugins/w3-total-cache/" rel="ugc">W3 Total Cache</a>) to concatenate and compress all the css and js, so the impact in performance will be minimum.
<h4>Languages</h4>
This syntax highlighter is based on <a href="http://google-code-prettify.googlecode.com/svn/trunk/README.html" rel="nofollow ugc">Google Code Prettify</a> and should work on a number of languages including C and friends, Java, Python, Bash, SQL, HTML, XML, Javascript, Makefiles, and Rust. It works passably on Ruby, PHP, VB, and Awk and a decent subset of Perl and Ruby, but, because of commenting conventions, doesn’t work on Smalltalk.
Other languages are supported via an extension (plugin options): CSS, SQL, YAML, Visual Basic, Clojure, Scala, Latek (TeX, LaTeX), WikiText, Erlang, Go, Haskell, Lua, OCAML, SML, F#, Nemerle, Protocol Buffers, CHDL (VHDL), XQ (XQuery), Lisp, Scheme, Dart, Llvm, Mumps, Pascal, R, S, RD, TCL
<h4>Styles</h4>
Four different styles are provided, and they can be previewed in the plugin options. They are modified to make sure they don’t clash with any other styles in your theme.
You have also the option to include your custom style.
If you have a style that would like to see included in the option list, just <a href="http://www.frontendmatters.com/contact/" rel="nofollow ugc">contact me</a>, or <a href="https://github.com/jesucarr/wordpress-prettify-code-syntax" rel="nofollow ugc">fork me</a>.
<h4>Notes</h4>
<ul>
<li>
Plugin options are at Settings > Prettify Code Syntax. Have a look at the Screenshots tab to see how it looks like.
</li>
<li>
If you don’t care too much about the HTML5 recommendation, you can skip the <code>language-</code> class. The code always gets detected automatically.
</li>
<li>
It will also work if you only use a <code>pre</code> tag without the <code>code</code> tag (but long lines will be wrapped instead of get horizontal scroll), or if you only use a <code>code</code> tag with the <code>prettyprint</code> class (but if you don’t use <code>pre</code> your spaces/returns won’t be maintained.)
</li>
<li>
Be careful using the Visual Editor tab when inserting code, as some HTML tags will be modified or removed.
</li>
<li>
Using a chaching plugin like W3 Total Cache is highly recommended.
</li>
</ul>
<h4>Demo</h4>
You can find a <a href="http://www.frontendmatters.com/open-source/wordpress-plugins/prettify-code-syntax/" rel="nofollow ugc">front end demo</a> here a the bottom.

Prettify Code Syntax

Code syntax highlighter using Google Prettify, supporting the HTML5 recommendation, and caching plugins.

Hover Highlights – Editor highlighting vs Prettify Code Syntax