Activating a script for a different format by adding an option to the File menu

[sfederici]

I managed to design a strategy to convert all custom FOREVER IF blocks of my custom TW desktop to IF blocks inside FOREVER blocks.

Now I would like to add an option to the File menu such as "Save it as Scratch sb3..." so to trigger the new script that will convert and save to sb3 all FOREVER IF blocks.

What I don't have the slightest idea is how menus are handled in Scratch/TW. I found several cryptic -to me- css/js/jsx files all named menu-something that I really don't understand.

Any help is welcome.