this will load a UI/glade file using GTK builder and will bind objects from the UI to a go struct using the struct field tag as an ID

gtk.go

package main

import (
	"fmt"
	"log"
	"reflect"

	"github.com/gotk3/gotk3/gtk"
)

type ApplicationWindow struct {
	Name string
	ID   *gtk.ApplicationWindow `gtk:"window"`
}

func bindUI(filename string, ui interface{}) error {
	content, err := gtk.BuilderNewFromFile(filename)
	if err != nil {
		return fmt.Errorf("Can't read file %w", err)
	}

	ptr := reflect.ValueOf(ui)
	val := ptr.Elem()
	st := val.Type()

	for i := 0; i < st.NumField(); i++ {
		field := st.Field(i)
		id := field.Tag.Get("gtk")
		if id == "" {
			continue
		}

		obj, err := content.GetObject(id)
		if err != nil {
			return fmt.Errorf("Unable to find object %s for field %s, err: %w", id, field.Name, err)
		}

		val.Field(i).Set(reflect.ValueOf(obj))
	}

	return nil
}

func main() {
	gtk.Init(nil)
	win := ApplicationWindow{}
	win.Name = "hello"
	err := bindUI("interface/app.glade", &win)
	if err != nil {
		log.Fatal(err)
	}
	fmt.Printf("%s\n", win.Name)

	win.ID.ShowAll()
	win.ID.Connect("destroy", func() {
		gtk.MainQuit()
	})

	gtk.Main()
}