Ensure Tag Browser recount is always called in the GUI thread.

src/calibre/gui2/__init__.py

@@ -592,6 +592,11 @@ def is_ok_to_use_qt():
         gui_thread = QThread.currentThread()
     return gui_thread is QThread.currentThread()
 
+def is_gui_thread():
+    global gui_thread
+    return gui_thread is QThread.currentThread()
+
+
 def find_forms(srcdir):
     base = os.path.join(srcdir, 'calibre', 'gui2')
     forms = []

src/calibre/gui2/tag_view.py

@@ -12,7 +12,7 @@ from itertools import izip
 from PyQt4.Qt import Qt, QTreeView, QApplication, \
                      QFont, SIGNAL, QSize, QIcon, QPoint, \
                      QAbstractItemModel, QVariant, QModelIndex
-from calibre.gui2 import config, NONE
+from calibre.gui2 import config, NONE, is_gui_thread, Dispatcher
 from calibre.utils.search_query_parser import saved_searches
 from calibre.library.database2 import Tag
 
@@ -54,6 +54,9 @@ class TagsView(QTreeView):
         self.model().clear_state()
 
     def recount(self, *args):
+        if not is_gui_thread():
+            # Re-call in GUI thread
+            return Dispatcher(self.recount)(*args)
         ci = self.currentIndex()
         if not ci.isValid():
             ci = self.indexAt(QPoint(10, 10))

src/calibre/gui2/ui.py

@@ -536,7 +536,7 @@ class Main(MainWindow, Ui_MainWindow, DeviceGUI):
         self.connect(self.library_view.model(),
                 SIGNAL('count_changed(int)'), self.location_view.count_changed)
         self.connect(self.library_view.model(), SIGNAL('count_changed(int)'),
-                     self.tags_view.recount)
+                     self.tags_view.recount, Qt.QueuedConnection)
         self.connect(self.search, SIGNAL('cleared()'), self.tags_view_clear)
         self.connect(self.saved_search, SIGNAL('changed()'), self.tags_view.recount, Qt.QueuedConnection)
         if not gprefs.get('quick_start_guide_added', False):