avoid stepping outside of context -- plain zero_var_indexes should be sufficient;
quick_and_dirty := true;
use_thys [
"Preface",
"Synopsis",
"Framework",
"First_Order_Logic",
"Outer_Syntax",
"Document_Preparation",
"Spec",
"Proof",
"Inner_Syntax",
"Misc",
"Generic",
"HOL_Specific",
"Quick_Reference",
"Symbols",
"ML_Tactic"
];