dialog.py3

#!/usr/bin/python3

import gi
gi.require_version('Gtk', '3.0')
from gi.repository import Gtk, Gdk

hints = Gdk.Geometry()
hints.min_width = 600
hints.min_height = 400

window = Gtk.Window()
window.connect("destroy", lambda w: Gtk.main_quit())
window.set_title("Dialog?")
window.set_geometry_hints(None, hints, Gdk.WindowHints.MIN_SIZE)
accel_group = Gtk.AccelGroup()
accel_group.connect(ord('q'), Gdk.ModifierType.CONTROL_MASK, Gtk.AccelFlags.LOCKED, Gtk.main_quit)
window.add_accel_group(accel_group)

#**********************************************
window.set_type_hint(Gdk.WindowTypeHint.DIALOG)
#**********************************************

window.show_all()
Gtk.main()