Make File→Exit button functional

Lays groundwork for signal callbacks.

contact.scm

@@ -41,7 +41,17 @@
 
 ;; Initialize the window.
 (define (init-window window)
+  (window-callbacks window)
   (qt:show window))
 
 
+;; Connect callback functions to widgets’ signals.
+(define (window-callbacks window)
+  (let ([file→exit (qt:find window "actionQuit")])
+    (if file→exit
+        (qt:connect
+         file→exit "triggered()"
+         (qt:receiver exit)))))
+
+
 (init)