Fix #754154 (Option to change default Library button behaviour)

src/calibre/gui2/actions/__init__.py

@@ -145,7 +145,6 @@ class InterfaceAction(QObject):
                     ans[candidate] = zf.read(candidate)
         return ans
 
-
     def genesis(self):
         '''
         Setup this plugin. Only called once during initialization. self.gui is

src/calibre/gui2/actions/choose_library.py

@@ -8,7 +8,7 @@ __docformat__ = 'restructuredtext en'
 import os, shutil
 from functools import partial
 
-from PyQt4.Qt import QMenu, Qt, QInputDialog
+from PyQt4.Qt import QMenu, Qt, QInputDialog, QToolButton
 
 from calibre import isbytestring
 from calibre.constants import filesystem_encoding
@@ -88,6 +88,9 @@ class ChooseLibraryAction(InterfaceAction):
                 type=Qt.QueuedConnection)
 
         self.stats = LibraryUsageStats()
+        self.popup_type = (QToolButton.InstantPopup if len(self.stats.stats) > 1 else
+                QToolButton.MenuButtonPopup)
+
         self.create_action(spec=(_('Switch/create library...'), 'lt.png', None,
             None), attr='action_choose')
         self.action_choose.triggered.connect(self.choose_library,
@@ -123,6 +126,7 @@ class ChooseLibraryAction(InterfaceAction):
                     type=Qt.QueuedConnection)
             self.choose_menu.addAction(ac)
 
+
         self.rename_separator = self.choose_menu.addSeparator()
 
         self.maintenance_menu = QMenu(_('Library Maintenance'))
@@ -172,6 +176,7 @@ class ChooseLibraryAction(InterfaceAction):
             return
         db = self.gui.library_view.model().db
         locations = list(self.stats.locations(db))
+
         for ac in self.switch_actions:
             ac.setVisible(False)
         self.quick_menu.clear()

src/calibre/gui2/layout.py

@@ -7,9 +7,9 @@ __docformat__ = 'restructuredtext en'
 
 from functools import partial
 
-from PyQt4.Qt import QIcon, Qt, QWidget, QToolBar, QSize, \
-    pyqtSignal, QToolButton, QMenu, \
-    QObject, QVBoxLayout, QSizePolicy, QLabel, QHBoxLayout, QActionGroup
+from PyQt4.Qt import (QIcon, Qt, QWidget, QToolBar, QSize,
+    pyqtSignal, QToolButton, QMenu,
+    QObject, QVBoxLayout, QSizePolicy, QLabel, QHBoxLayout, QActionGroup)
 
 
 from calibre.constants import __appname__