Use self.close rather than self.destroy for quit action

Fixes a problem where window hangs on quit.  Closes PacktPublishing#12.

Author: alandmoore

Chapter03/calendar_app.py

@@ -27,7 +27,10 @@ def __init__(self):
         self.layout().addWidget(self.submit_btn)
         self.cancel_btn = qtw.QPushButton(
             'Cancel',
-            clicked=self.destroy
+            # Errata:  The book contains this line:
+            #clicked=self.destroy
+            # It should call self.close instead, like so:
+            clicked=self.close
             )
         self.layout().addWidget(self.cancel_btn)
         self.show()

Chapter04/text_editor.py

@@ -94,7 +94,10 @@ def __init__(self):
         file_menu.addSeparator()
 
         # add an action with a callback
-        quit_action = file_menu.addAction('Quit', self.destroy)
+        # Errata:  The book contains this line:
+        #quit_action = file_menu.addAction('Quit', self.destroy)
+        # It should call self.close instead, like so:
+        quit_action = file_menu.addAction('Quit', self.close)
 
         # connect to a Qt Slot
         edit_menu.addAction('Undo', self.textedit.undo)