bug#51716: 29.0.50; [PATCH] Expose xwidget navigation history to Lisp code

[Eli Zaretskii <eliz@gnu.org>]

> From: Po Lu <luangruo@yahoo.com>
> Cc: 51716@debbugs.gnu.org
> Date: Tue, 09 Nov 2021 21:44:47 +0800
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > Before I dive into the code, let me ask: why not use the usual Emacs
> > history machinery for this?  IOW, have some xwidget-specific history
> > variable that would store the browsing history, and use that variable
> > in conjunction with foo-prev and foo-next commands?  Why do we need to
> > reinvent the wheel for xwidgets, and why do that in C?
> 
> WebKit stores navigation history specially.  For instance, it implements
> a feature where malicious (i.e. looping) redirects are not recorded in
> history.  This is not available from Lisp, as the signals exposed by
> WebKitGTK are insufficient to keep track of that data.  Further, I think
> there is a way for web pages to tell WebKitGTK whether or not to record
> themselves in history, which also cannot be implemented separately.
> 
> It can only be done from C, because the necessary information is only
> available in C.

Please give more details, because I still have only a very vague idea
of the problems you mention, and why they absolutely preclude mapping
the browsing history into Lisp.