diff --git a/src/calibre/gui2/__init__.py b/src/calibre/gui2/__init__.py
index fed22f87e2..870010b168 100644
--- a/src/calibre/gui2/__init__.py
+++ b/src/calibre/gui2/__init__.py
@@ -2,9 +2,11 @@ __license__   = 'GPL v3'
 __copyright__ = '2008, Kovid Goyal <kovid at kovidgoyal.net>'
 """ The GUI """
 import os
+from threading import RLock
+
 from PyQt4.QtCore import QVariant, QFileInfo, QObject, SIGNAL, QBuffer, Qt, QSize, \
                          QByteArray, QTranslator, QCoreApplication, QThread, \
-                         QEvent
+                         QEvent, QTimer
 from PyQt4.QtGui import QFileDialog, QMessageBox, QPixmap, QFileIconProvider, \
                         QIcon, QTableView, QApplication, QDialog, QPushButton
 
@@ -533,6 +535,8 @@ class Application(QApplication):
         self._translator = None
         self.load_translations()
         qt_app = self
+        self._file_open_paths = []
+        self._file_open_lock = RLock()
 
         if islinux:
             self.setStyleSheet('''
@@ -545,6 +549,11 @@ class Application(QApplication):
                     }
             ''')
 
+    def _send_file_open_events(self):
+        with self._file_open_lock:
+            self.file_event_hook(self._file_open_paths)
+            self._file_open_paths = []
+
 
     def load_translations(self):
         if self._translator is not None:
@@ -557,7 +566,9 @@ class Application(QApplication):
         if callable(self.file_event_hook) and e.type() == QEvent.FileOpen:
             path = unicode(e.file())
             if os.access(path, os.R_OK):
-                self.file_event_hook(path)
+                with self._file_open_lock:
+                    self._file_open_paths.append(path)
+                QTimer.singleShot(self._send_file_open_events, 1000)
             return True
         else:
             return QApplication.event(self, e)
diff --git a/src/calibre/gui2/ui.py b/src/calibre/gui2/ui.py
index c16b868b34..110224e4f2 100644
--- a/src/calibre/gui2/ui.py
+++ b/src/calibre/gui2/ui.py
@@ -988,15 +988,23 @@ class Main(MainWindow, Ui_MainWindow, DeviceGUI):
             self.cover_cache.refresh([cid])
             self.library_view.model().current_changed(current_idx, current_idx)
 
-    def add_filesystem_book(self, path, allow_device=True):
-        if os.access(path, os.R_OK):
-            books = [os.path.abspath(path)]
+    def _add_filesystem_book(self, paths, allow_device=True):
+        if isinstance(paths, basestring):
+            paths = [paths]
+        books = [os.path.abspath(path) for path in paths is os.access(path,
+            os.R_OK)]
+
+        if books:
             to_device = allow_device and self.stack.currentIndex() != 0
             self._add_books(books, to_device)
             if to_device:
                 self.status_bar.showMessage(\
                         _('Uploading books to device.'), 2000)
 
+
+    def add_filesystem_book(self, paths, allow_device=True):
+        Dispatcher(self._add_filesystem_book)(paths, allow_device=allow_device)
+
     def add_books(self, checked):
         '''
         Add books from the local filesystem to either the library or the device.
@@ -1042,11 +1050,11 @@ class Main(MainWindow, Ui_MainWindow, DeviceGUI):
                                 infos, on_card=on_card)
             self.status_bar.showMessage(
                     _('Uploading books to device.'), 2000)
-        if self._adder.number_of_books_added > 0:
+        if getattr(self._adder, 'number_of_books_added', 0) > 0:
             self.library_view.model().books_added(self._adder.number_of_books_added)
             if hasattr(self, 'db_images'):
                 self.db_images.reset()
-        if self._adder.critical:
+        if getattr(self._adder, 'critical', None) is not None:
             det_msg = []
             for name, log in self._adder.critical.items():
                 if isinstance(name, str):
@@ -1056,7 +1064,8 @@ class Main(MainWindow, Ui_MainWindow, DeviceGUI):
                     _('Failed to read metadata from the following')+':',
                     det_msg='\n\n'.join(det_msg), show=True)
 
-        self._adder.cleanup()
+        if hasattr(self._adder, 'cleanup'):
+            self._adder.cleanup()
         self._adder = None