/usr/lib/python2.7/dist-packages/menueditor/AddsubmenuDialog.py is in edubuntu-menueditor 1.3.5-0ubuntu2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/python2.7/dist-packages/menueditor/../../../../share/pyshared/menueditor/AddsubmenuDialog.py