Invalid class names allowed

You can add this kind of warning (and even apply your logic to fix the invalid name) by yourself by using selector:add event

editor.on('selector:add', selector => {
		const name = selector.get('name');

      	if (nameNotValid(name)) {
			alert('Class changed');
			selector.set({ name: `fixed-${name}` });
      	}
    });

That's perfect. Thank you!