bug#59862: quit-restore per window buffer

[martin rudalics via "Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>]

 > But there is no *scratch* in the list of previous buffers for 'C-x t t C-h i'
 > (that can be confirmed when tab-line is enabled), so the user won't expect
 > to show *scratch*.  And indeed the frame case doesn't show *scratch*.

'window--display-buffer' resets that window's previous buffers here

     (when (memq type '(window frame tab))
       (set-window-prev-buffers window nil))

In the "window" and "frame" case these are actually not needed because
when making a new window (on the same or a new frame), that window's
previous buffers are automatically set to nil - by make_window in the
release version and by the allocation routine with my patch.  I reset
them just to make sure.  When you show *info* in an already existing
window, that window's previous buffers are not reset.  So the presence
of "tab" in the form above is not entirely correct in this regard.

 > I hoped that it would be possible for the tab case to do the same,
 > but I don't know how the frame case is handled to do the right thing.

In 'quit-restore-window' you count the windows with a 'quit-restore'
parameter.  In the scenario at hand this gives 2 so you don't close the
tab.  If you told me in detail what this counting is supposed to
accomplish, I might be able to help you.

martin