method init : unit = (
Textvariable.set tv "1";
rads <- List.map
(fun (t, v) -> Radiobutton.create ~text:t ~value:v ~variable:tv ~borderwidth:1 optionFrame)
[("Over-Approximation ", "1"); ("Under-Approximation","2")];
match rads with [] -> ();
|[x] -> ();
|(x::y::_) -> (Radiobutton.select x;
Radiobutton.configure x ~command:(fun () -> Entry.configure levelEntry ~background:defcol ~state:`Disabled);
Radiobutton.configure y ~command:(fun () -> Entry.configure levelEntry ~background:selcol ~state:`Normal););
destroy levelLabel;
levelLabel <- Label.create ~text:"Level : " ~width:20 ~height:2 frame2;
destroy levelEntry;
levelEntry <- Entry.create ~width:20 ~background:defcol ~state:`Disabled frame2;
Checkbutton.configure agent ~command:(fun () -> (if agentString="" then agentString <- " --2AgentsOnly " else agentString <- ""));
pack ~side:`Top [optionFrame];
pack ~side:`Top [optionLabel];
pack ~side:`Top [verificationLabel];
pack ~side:`Top [agent];
pack ~side:`Top [knowledgeLabel];
pack rads;
pack ~side:`Top [frame2];
pack ~side:`Left [levelLabel];
pack ~side:`Right [levelEntry];)