Re-positioning Gtk widget with a mouse drag in Python (GTK4 version)

drag.py

#!/usr/bin/env python

import sys, gi, operator
gi.require_version('Gtk', '4.0')
gi.require_version('Adw', '1')
from gi.repository import Gtk, Adw, Gdk


class MainWindow(Gtk.ApplicationWindow):
    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.set_default_size(600, 400)
        self.set_title("Test Drag & Drop")
        self.fixed = Gtk.Fixed()
        self.set_child(self.fixed)

        self.image = Gtk.Image.new_from_icon_name('window-close-symbolic')
        self.image.set_pixel_size(64)
        self.fixed.put(self.image, 0, 0)

        controller = Gtk.GestureDrag()
        controller.connect('drag-begin', self.on_begin)
        controller.connect('drag-update', self.on_update)
        self.image.add_controller(controller)

    def on_begin(self, controller, start_x, start_y):
        self.diff = tuple(map(operator.sub, self.fixed.get_child_position(self.image), self.get_fixed_pos()))

    def on_update(self, controller, offset_x, offset_y):
        move = map(operator.add, self.get_fixed_pos(), self.diff)

        # bounding the movable widget inside the GtkFixed container
        max_width = self.fixed.get_width() - self.image.get_width()
        max_height = self.fixed.get_height() - self.image.get_height()
        move_x, move_y = map(min, (max_width, max_height), map(max, (0, 0), move))

        self.fixed.move(self.image, move_x, move_y)

    def get_fixed_pos(self):
        pointer = self.get_display().get_default_seat().get_pointer()
        _, px, py, _ = self.fixed.get_native().get_surface().get_device_position(pointer)
        return self.translate_coordinates(self.fixed, px, py)


class MyApp(Adw.Application):
    def __init__(self, **kwargs):
        super().__init__(**kwargs)
        self.connect('activate', self.on_activate)

    def on_activate(self, app):
        self.win = MainWindow(application=app)
        self.win.present()

app = MyApp(application_id="com.example.GtkApplication")
app.run(sys.argv)