bug#38354: 27.0.50; Implement display action display-buffer-in-tab

[Juri Linkov]

>>> In either case, do I read the code correctly that it can prefer a
>>> window in a non-current tab to a window in a current tab on another
>>> frame.  If so, do we want that?
>>
>> Do you think it should return a list of all tabs owning a window
>> with the buffer?
>
> No.  I meant that it should continue to scan frames as long as it has
> not found a window showing that buffer.  During that scan it would
> record the first tab that has a window whose buffer is the one searched
> for.  The return value would then be preferably (the tab of) a window
> actually showing the buffer or, if no such window exists, a tab that
> has a window whose buffer is the one searched for.
>
>> Why not?  Does display-buffer-reuse-window currently prefers
>> a window on the same frame even when a window on another frame
>> also shows the same buffer?
>
> It does.  But I don't say that 'display-buffer-in-tab' must do the
> same.  What I meant was, as sketched above, to prefer a tab where a
> window already shows the buffer to tabs that would show the buffer but
> only if they were current/active or tabs where such a buffer window
> would have to be added first.

I have no preference, but don't understand why the implementation
should provide only one way, but not another.  Is it what users expect?

>> Additional question: using quit-window on the buffer displayed
>> by display-buffer-in-tab should close its tab.  Could you recommend
>> how to implement this?  Maybe to add an additional argument CLOSE-TAB
>> to quit-restore-window?  e.g.
>>
>>    (defun quit-restore-window (&optional window bury-or-kill close-tab)
>>    ...
>>
>> For testing I tried to call '(tab-bar-close-tab)' at the end of
>> 'quit-restore-window' unconditionally, but sometimes it does wrong thing:
>> when quitting the last window of the frame closes the frame,
>> '(tab-bar-close-tab)' closes the tab on another frame that
>> is selected after closing the original frame.
>
> Then 'tab-bar-close-tab' is probably the wrong function to call here.
>
> But why do you want to close a tab (an entire window configuration)
> here?  Shouldn't 'quit-restore-window' just remove that window from a
> tab, that is, update the current tab of that frame to what it is?  Or
> does the current tab of a frame not necessarily match that frame's
> window configuration?

It should close the tab only on quitting the window with the buffer
whose displaying created the tab.  For example, when
'switch-to-buffer-other-tab' creates a new tab, then quitting
its buffer should close the tab.

This is the same logic as for creating/deleting the window, e.g.
'C-h f car RET' creates a window, but typing 'q' in Help buffer
deletes the window.  'q' in a new tab should close it as well.