By the way, can we implement syntax highlight for the language we choose from the start for preprocessing?

This will be very nice looking and convenient. +100 points to Zabbix feels and looks    And will help users not to make any stupid typos or syntax errors.

Like Prism or Rainbow:

https://prismjs.com/ (MIT), https://github.com/PrismJS/prism

https://craig.is/making/rainbows (Apache 2.0), https://github.com/ccampbell/rainbow/blob/master/LICENSE

They seem to be small, embeddedable JS libraries with permissive license

And if we like it, we may write a plugin for it (prism?) to highlight the syntax of Zabbix trigger expressions as well.