Visual Novel Maker provides a powerful Script Editor allowing you to change the whole Visual Novel engine if you like.

Scripts

On the left side you can see all scripts of your game. You can organize your script in any way you want using folders. Each folder internally is handled like a script and can even contain script code itself.  The programming language used for game scripting is CoffeeScript which compiles to JavaScript, see www.coffeescript.org for more information. If you don't like to work with CoffeeScript, you can just create JavaScript files as well.

Whenever you save your project, all edited scripts are compiled to JavaScript and you get informed about syntax errors. If there is a syntax error, just fix it and then save your project again.

The Script / Code Editor

On the right side you can see the Code Editor showing you the content of your current selected script. Visual Novel Maker uses ACE Code Editor, see www.ace.c9.io for more information about ACE itself. You can use CTRL+,(COMMA) or CMD+,(Comma) to open ACE settings where you can change things like font size, etc.