Livecode offers exactly what you're describing: GUI editing of a live user interface, with code able to be built-in to every object. https://livecode.com https:

Livecode offers exactly what you're describing: GUI editing of a live user interface, with code able to be built-in to every object. https://livecode.com https://livecode.com It's based on HyperCard, so the language isn't to everyone's taste. But it's updated to include color, unicode, more advanced coding techniques, database access, multi-platform and more. But the basic concept -- I want a button here, and a field there, and a slider there -- is still 100% there.