...

src/calibre/gui2/keyboard.py

@@ -10,6 +10,7 @@
 from collections import OrderedDict
 from functools import partial
 
+import sip
 from PyQt4.Qt import (QObject, QKeySequence, QAbstractItemModel, QModelIndex,
         Qt, QStyledItemDelegate, QTextDocument, QStyle, pyqtSignal, QFrame,
         QApplication, QSize, QRectF, QWidget, QTreeView,
@@ -125,11 +126,18 @@ def finalize(self):
         #pprint.pprint(self.keys_map)
 
     def replace_action(self, unique_name, new_action):
+        '''
+        Replace the action associated with a shortcut. If this method returns
+        False you must call finalize() to have shortcuts set on the new action
+        correctly.
+        '''
         sc = self.shortcuts[unique_name]
         ac = sc['action']
-        if ac is not None:
+        if ac is not None and not sip.isdeleted(ac):
             new_action.setShortcuts(ac.shortcuts())
             ac.setShortcuts([])
+            return True
+        return False
 
 # }}}