bug#54038: 29.0.50; doc-view cannot show different pages in different tabs

[martin rudalics <rudalics@gmx.at>]

 >> We might be able to provide such a function but can you tell me why you
 >> would need it and how you would use it?
 >
 > It could be used in 'image-mode-winprops':
 >
 >    (when cleanup
 >      (setq image-mode-winprops-alist
 >    	  (delq nil (mapcar (lambda (winprop)
 > 			      (let ((w (car-safe winprop)))
 > 				(if (or (not (windowp w))
 >                                          (window-live-p w)
 >             new function =>              (window-live-in-all-window-configurations w))
 > 				    winprop)))
 >    			    image-mode-winprops-alist))))

I can't tell from here what 'window-live-in-all-window-configurations'
is supposed to return.  Its name appears misleading - do we care if 'w'
is live in a configuration of another frame but w's?  So please tell me
the doc-string of ‘window-live-in-all-window-configurations’ first.

And please always keep in mind: The only agent that has access to _all_
window configurations is the garbage collector.  If we wanted to change
that, we'd have to make window configurations explicitly deletable like
buffers or windows with functions like 'make-window-configuration',
'delete-window-configuration' and 'window-configurations-list'.  While
this might not pose great problems for read_minibuf, it certainly will
for configurations in plain Lisp code which all of a sudden would become
noncollectable after the last reference to them has gone ...

martin