bug#71386: 29.1; Frame is auto-deleted even when it has multiple tabs

[Juri Linkov]

>> If I open a frame with multiple tabs, and one of the tabs has
>> a dedicated window, then kill the buffer with the dedicated window,
>> the frame is deleted along with its tabs.
>> 
>> I understand that this is the documented behaviour, however my
>> expectation is that the tab should be deleted but the frame should
>> stay when other tabs are available, similar to how the frame is not
>> deleted if other windows are visible.
>
> I'm not sure I agree with you.  Tabs are just saved frame
> configurations, they are not real windows.  If we make this behavior
> dependent on tab-bar-mode, we basically introduce an incompatible
> behavior change in this particular case, which people and Lisp
> programs out there might not expect or like.
>
> I'm adding Juri and Martin to this discussion.

I don't understand the logic of window--delete.  But maybe
window-deletable-p should also check for existing tabs in tab-bar-mode
and return 'tab' instead of 'frame'.  Then window--delete
could close the tab instead of deleting the frame.