Juri Linkov <juri@linkov.net> writes:

>> +(defvar tab-line-tabs-window-buffers-function
>> +  #'tab-line-tabs-window-buffers-default
>> +  "Function for get a list of window buffers.
>> +Used only for `tab-line-tabs-fixed-window-buffers'.")
>
> I wonder why do you need another indirection.  It should be
> sufficient to use tab-line-tabs-window-buffers-filter-function
> in the current implementation of tab-line-tabs-window-buffers,
> especially with the value 'identity' to keep current behavior.

That was to add a simple way to customize the listed buffers in
'tab-line-tabs-fixed-window-buffers', not to be another filter.  I've
reverted it anyways: