Edit Book: Allow drag and drop of files onto dock icon on OS X

src/calibre/gui2/tweak_book/boss.py

@@ -242,6 +242,10 @@ class Boss(QObject):
 
         :param edit_file: The name of a file inside the newly opened book to start editing. Can also be a list of names.
         '''
+        if isinstance(path, (list, tuple)) and path:
+            # Can happen from an file_event_hook on OS X when drag and dropping
+            # onto the icon in the dock or using open -a
+            path = path[-1]
         if not self._check_before_open():
             return
         if not hasattr(path, 'rpartition'):

src/calibre/gui2/tweak_book/main.py

@@ -25,6 +25,14 @@ files inside the book which will be opened for editing automatically.
     setup_gui_option_parser(parser)
     return parser
 
+class EventAccumulator(object):
+
+    def __init__(self):
+        self.events = []
+
+    def __call__(self, ev):
+        self.events.append(ev)
+
 def gui_main(path=None, notify=None):
     _run(['ebook-edit', path], notify=notify)
 
@@ -55,6 +63,7 @@ def _run(args, notify=None):
     decouple('edit-book-')
     override = 'calibre-edit-book' if islinux else None
     app = Application(args, override_program_name=override, color_prefs=tprefs)
+    app.file_event_hook = EventAccumulator()
     app.load_builtin_fonts()
     app.setWindowIcon(QIcon(I('tweak.png')))
     Application.setOrganizationName(ORG_NAME)
@@ -64,6 +73,11 @@ def _run(args, notify=None):
     main.show()
     if len(args) > 1:
         main.boss.open_book(args[1], edit_file=args[2:], clear_notify_data=False)
+    else:
+        for path in reversed(app.file_event_hook.events):
+            main.boss.open_book(path)
+            break
+        app.file_event_hook = main.boss.open_book
     app.exec_()
     # Ensure that the parse worker has quit so that temp files can be deleted
     # on windows