Workaround for Qt 5 regression that prevented the keyboard shortcuts …

…for the various Similar books actions from working

src/calibre/gui2/actions/similar_books.py

@@ -9,6 +9,7 @@
 
 from PyQt5.Qt import QToolButton
 
+from calibre.constants import isosx
 from calibre.gui2.actions import InterfaceAction
 
 class SimilarBooksAction(InterfaceAction):
@@ -30,6 +31,11 @@ def genesis(self):
             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)