More general fix for the OS X keyboard shortcuts not working problem. Fixes #1360849 [m command to merge books no longer functions](https://bugs.launchpad.net/calibre/+bug/1360849)

Add all actions created using the create_action/create_menu_action API
directly to the main window this allows their shortcuts to work on OS X.

src/calibre/gui2/actions/__init__.py

@@ -12,6 +12,7 @@ from PyQt5.Qt import (QToolButton, QAction, QIcon, QObject, QMenu,
         QKeySequence)
 
 from calibre import prints
+from calibre.constants import isosx
 from calibre.gui2 import Dispatcher
 from calibre.gui2.keyboard import NameConflict
 
@@ -191,7 +192,11 @@ class InterfaceAction(QObject):
                         pass
                     shortcut_action.setShortcuts([QKeySequence(key,
                         QKeySequence.PortableText) for key in keys])
-
+                else:
+                    if isosx:
+                        # In Qt 5 keyboard shortcuts dont work unless the
+                        # action is explicitly added to the main window
+                        self.gui.addAction(shortcut_action)
 
         if attr is not None:
             setattr(self, attr, action)
@@ -253,6 +258,10 @@ class InterfaceAction(QObject):
             self.gui.keyboard.register_shortcut(unique_name,
                 shortcut_name, default_keys=keys,
                 action=ac, description=description, group=self.action_spec[0])
+            if isosx:
+                # In Qt 5 keyboard shortcuts dont work unless the
+                # action is explicitly added to the main window
+                self.gui.addAction(ac)
         if triggered is not None:
             ac.triggered.connect(triggered)
         return ac

src/calibre/gui2/actions/similar_books.py

@@ -9,7 +9,6 @@ from functools import partial
 
 from PyQt5.Qt import QToolButton
 
-from calibre.constants import isosx
 from calibre.gui2.actions import InterfaceAction
 
 class SimilarBooksAction(InterfaceAction):
@@ -31,11 +30,6 @@ class SimilarBooksAction(InterfaceAction):
             ac = self.create_action(spec=(text, icon, None, shortcut),
                     attr=target)
             m.addAction(ac)
-            if isosx:
-                # For some reason with Qt 5 the keyboard shortcuts for these
-                # actions dont work unless the actions are added to the main
-                # window
-                self.gui.addAction(ac)
             ac.triggered.connect(partial(self.show_similar_books, target))
         self.qaction.setMenu(m)