Mathematica Help Browser from Mathematica 5 in new versions of Mathematica

I remember that someone from WRI stated in the official newsgroup that Mathematica开发者_JAVA百科 7 still has a working old-fashioned Mathematica Help Browser from Mathematica 5 for compatibility purposes. But I can not find the post where the code for invoking it is given.

How to invoke and use this legacy Help Browser in new versions of Mathematica?

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The old browser will show up if you try to look at documentation for packages that were written in the old format. From the main documentation page, click 'Add-Ons and Packages' at the very bottom-left, and then click on the old package name. Based on what I have installed, it looks like the old packages will have a little orange square in front of them, instead of a triangle that shows/hides additional information.

The old browser is only used for old documentation.

I assume you're aware of the 'Function Navigator' and 'Virtual Book' which provide alternate ways of navigating the new documentation.

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At this moment I have found two ways to invoke the legacy Help Browser by clicking a button:

DisplayForm@ButtonBox["Preface",
    BaseStyle -> "AddOnsLinkText",
    Active -> True,
    ButtonData :> {"PCT Preface", None}]

and

DisplayForm@
 ButtonBox[" »", BaseStyle -> "Link", Evaluator -> Automatic, 
  ButtonFunction :> (PacletManager`Package`helpBrowserLookup[#] &), 
  ButtonData -> "Help Browser"]

I found that we have the global option HelpBrowserSettings that specifies settings for the legacy Help Browser.

And we still have working functions HelpBrowserLookup and HelpBrowserNotebook (now undocumented) and command FrontEndTokenExecute["RebuildHelpIndex"] for rebuilding the help index of the legacy Help Browser.