Merge from trunk

src/calibre/gui2/preferences/main.py

@@ -357,7 +357,6 @@ class Preferences(QMainWindow):
                 bytearray(self.saveGeometry()))
         if self.committed:
             self.gui.must_restart_before_config = self.must_restart
-            self.gui.tags_view.set_new_model() # in case columns changed
             self.gui.tags_view.recount()
             self.gui.create_device_menu()
             self.gui.set_device_menu_items_state(bool(self.gui.device_connected))

src/calibre/gui2/preferences/search.py

@@ -173,7 +173,7 @@ class ConfigWidget(ConfigWidgetBase, Ui_Form):
     def refresh_gui(self, gui):
         gui.set_highlight_only_button_icon()
         if self.muc_changed:
-            gui.tags_view.set_new_model()
+            gui.tags_view.recount()
         gui.search.search_as_you_type(config['search_as_you_type'])
         gui.search.do_search()
 

src/calibre/gui2/tag_browser/view.py

@@ -571,9 +571,10 @@ class TagsView(QTreeView): # {{{
     def show_item_at_index(self, idx, box=False,
                            position=QTreeView.PositionAtCenter):
         if idx.isValid() and idx.data(Qt.UserRole).toPyObject() is not self._model.root_item:
-            self.setCurrentIndex(idx)
+            self.setExpanded(idx, True) # Needed otherwise Qt segfaults if the
+                                        # node is buried in a collapsed, off
+                                        # screen hierarchy
             self.scrollTo(idx, position)
-            self.setCurrentIndex(idx)
             if box:
                 self._model.set_boxed(idx)