bug#37667: 27.0.50; Tab Bar display problems with more than 5 tabs

[Juri Linkov <juri@linkov.net>]

>> >> 2. Disable wrapping to the second line since it's not supported in -nw;
>> >
>> > Why isn't it supported on TTY frames, btw?  It seemed to me that the
>> > infrastructure is there, i.e. we can have FRAME_TAB_BAR_LINES(f) > 1,
>> > it's just that the code doesn't consider this possibility.
>>
>> Is it possible for TTY frames to use the same code that implements
>> wrapping in multi-line tab-bar on graphical displays?
>
> I don't think I understand the question.  Which details of wrapping
> multi-line tab bars seem to prevent doing the same on TTY frames?

I meant using the existing function tab_bar_height whose value increases
FRAME_TAB_BAR_LINES, but TTY doesn't use FRAME_TAB_BAR_LINES.

>> 5. There is another alternative: display arrow buttons on both sides
>>    of the tab-bar, clicking on arrows will hscroll tabs.
>
> On GUI frames, you get this for free by using the hscrolling machinery
> and line truncation.

What is needed to enable it?  Does hscrolling depend on the position of point
so point should be moved to the current tab to center other tabs around it?

Also I tried to insert newlines in the tab-bar string, without success.

>> 6. Or even better: clicking on such arrow buttons will pop up a menu of
>>    remaining tabs that don't fit into one-line tab-bar.
>>    This is like implemented recently for Info-history where clicking on
>>    the tool-bar arrow pops up a menu of previous Info nodes.  The same way
>>    clicking on the arrows on the tab-bar could pop up a menu of tabs whose
>>    names don't fit into the one-line tab-bar at both sides of the current tab.
>
> I'd leave such fancy features for future releases.  Remember: we are
> waiting for this and other new features to reach some reasonable state
> in order to start the Emacs 27 release cycle.

This is the simplest and quickest option to implement.  For Info-history
it took just 20 lines of Lisp code.