diff -r da5f1fa46f2b -r fb73a6b6622d controls/LibraryPanel.py
--- a/controls/LibraryPanel.py	Thu Oct 19 10:57:35 2017 +0300
+++ b/controls/LibraryPanel.py	Thu Oct 19 11:03:03 2017 +0300
@@ -232,7 +232,7 @@
                     # Tree item doesn't exist, add new one to category item
                     else:
                         blocktype_item = self.Tree.AppendItem(
-                                            category_item, blocktype["name"])
+                            category_item, blocktype["name"])
                         # See comment when adding category
                         if wx.Platform != '__WXMSW__':
                             blocktype_item, category_cookie = \