Fix #3664 (Program Crashes When Attempting to Add Books to 0.6.15)

src/calibre/gui2/tag_view.py

@@ -147,6 +147,7 @@ class TagsModel(QAbstractItemModel):
             state_map = dict(izip(names, states))
             category_index = self.index(i, 0, QModelIndex())
             if len(category.children) > 0:
+                r, self.rowCount(category_index)
                 self.beginRemoveRows(category_index, 0,
                         len(category.children)-1)
                 category.children = []
@@ -167,6 +168,13 @@ class TagsModel(QAbstractItemModel):
         item = index.internalPointer()
         return item.data(role)
 
+    def headerData(self, *args):
+        return NONE
+
+    def flags(self, *args):
+        return Qt.ItemIsEnabled|Qt.ItemIsSelectable
+
+
     def index(self, row, column, parent):
         if not self.hasIndex(row, column, parent):
             return QModelIndex()