grettke

Out of the box, <a href="https://wordpress.org/extend/plugins/wp-syntax/" rel="ugc">WP-Syntax</a> 
colors code using the default <a href="http://qbnz.com/highlighter/" rel="nofollow ugc">GeSHi</a> colors. 
Per the authors advice in the ‘Advanced Customization’ section of 
<a href="https://wordpress.org/extend/plugins/wp-syntax/other_notes/" rel="ugc">Other Notes</a>, 
you can configure GeSHi yourself by handling the <code>wp_syntax_init_geshi</code> 
hook and configuring it programmatically.
Since I wanted to do just that, I decided to publish a generic plugin 
for folks who wanted to configure GeSHi following this approach.
<h3>Release Notes</h3>
1.2 : Set keyword expansion in the plugin file. Uses Wp-Syntax 0.9, which depends on GeSHi 1.0.7.22.
1.1 : Fixed grammatical errors in the readme.txt. Uses Wp-Syntax 0.9, which depends on GeSHi 1.0.7.22.
1.0 : First public release. Uses Wp-Syntax 0.9, which depends on GeSHi 1.0.7.22.

wp-syntax-rettke

wp-syntax-rettke serves as an example for the programmatic 
"Advanced Configuration" of GeSHi in Ryan McGeary's excellent WP-Syntax plu …

cssdaily

HTML Block with Highlighting is a WordPress plugin which adds a new HTML Block with syntax highlighting to the Gutenberg editor.

HTML Block with Highlighting

HTML Block with Highlighting is a WordPress plugin which adds a new HTML Block with syntax highlighting to the Gutenberg editor.

wp-syntax-rettke vs HTML Block with Highlighting