clear_undo replaced by clear_undos; title replaced by header;
clear_undo replaced by clear_undos;
title replaced by header;

MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle