Source for CommonQt Tutorial #1: Hello World

helloworld.lisp

(ql:quickload :qt)
(in-package :qt) 
(named-readtables:in-readtable :qt)

(defclass hello-world-app () ()
    (:metaclass qt-class)
    (:qt-superclass "QWidget"))
    
(defmethod initialize-instance :after ((instance hello-world-app) &key)
    (new instance)
    (#_setGeometry instance 200 200 300 300)
    (#_setWindowTitle instance "Hello World!"))

(make-qapplication)
(with-main-window (window (make-instance 'hello-world-app)))