import gi
gi.require_version("Gtk", "3.0")

from gi.repository import Gtk, GLib

w = Gtk.Window()
l = Gtk.Label()
l.set_padding(12, 12)
l.set_markup("blaaaaasdadasdsad\nblaaaaasdadasdsad")

w.add(l)
w.show_all()
GLib.unix_signal_add(0, 2, Gtk.main_quit)
Gtk.main()
