= tabs: mktabs, tabsctl: tabbed notebook pseudo-widget     include "tabs.m";    tabs := load Tabs Tabs->PATH;     init:        fn();     mktabs:      fn(p: ref Tk->Toplevel, book: string,                   tabs: array of (string, string), dflt: int):                   chan of string;     tabsctl:     fn(p: ref Tk->Toplevel, book: string,                   tabs: array of (string, string), curid: int,                   newid: string): int; Tabs  implements a Tk extension: a user-interface device thatlooks like a tabbed notebook. Init should be called once to initialise the internal state. Mktabs creates a tabbed notebook  pseudo  widget,  book,  forinsertion into Tk widget p.  Once created, book can be packedlike any other Tk widget.  Information for specific tab pagesis contained in the tabs array.  For each page, tabs containsthe name displayed in the tab and a Tk widget name.  Whenevera  page  is  selected,  its widget is packed in book and dis‐played.  The notebook will initially display the page indexedby  dflt.   Mktabs  returns  a  Tk  event  channel.  Messagesreceived on this channel should be passed as the newid  argu‐ment to tabsctl. Tabsctl  controls  a  tabbed notebook.  Curid is the index ofthe page currently selected in  the  notebook.   Newid  is  astring  containing the index of the new page to be displayed;this is usually the information received on the tabs channel.The index of the newly selected page is returned. == source/appl/lib/tabs.b == see ALSOdividers(2), draw-context(2), tk(2), wmlib(2)