bug#38624: 27.0.50; [wish] tab navigation via keyboard should mimic buffer navigation

[Juri Linkov <juri@linkov.net>]

>> So you propose to bind it
>> to the key 'C-x t t'?  This key is the most convenient to type,
>> so it should be used for the most frequently used tab command.
>> Do you think 'tab-bar-switch-to-tab' would be the most frequently
>> used command?
>
> I do not have used tabs much, but would assume the most frequent
> action would switching tabs.  I modeled this key stroke after
> switch-to-buffer.  And the other one (see below) after buffer-list.

The key sequence for switching tabs doesn't need to be the easiest
to type, because after running it, the user still needs to type
the tab name to switch to, that requires more key strokes anyway.

>> Actually, tab-list was designed to not destroy the window configuration.
>> Unlike ibuffer or list-buffers that split the window, tab-list can't do
>> the same.  If tab-list will split the window, then after selecting
>> another tab in the list and later going back to the same tab, will
>> still display the window with tab-list, and the same window will be
>> presented in every tab that would be annoying.  Thus tab-list
>> takes care to not break user's window configurations.
>
> Perhaps this window could be buried before switching tabs (see below).

Maybe using quit-window before switching tabs, although this might
cause other problems.

Another problem is what to do when the user uses the tab list to delete
the current window configuration (i.e. where the tab list is shown),
this might have unexpected effect.

Neither there is no "*Buffer List*" buffer in the list of buffers
displayed by 'list-buffers', nor there is no "*Ibuffer*" buffer in
the list of buffers displayed by 'ibuffer'.  That's because they
don't allow killing the same buffer where the buffer list is shown.
Should the tab list allow deleting the tab where the tab list is shown?

>> Or do you want to use tab-list for other purposes,
>> not for selecting a tab from the list?
>
> I assumed that tab list shows a buffer for managing tabs.
> Create, delete, perhaps regroup them.  And perhaps users would
> like to have a dedicated tab (leftmost?) for that.  I personally
> will use this feater via keyboard and therefore it is not
> important for me to have a dedicated tab list tab.

Thanks for your explanation, now it's clear what you expected from this,
so you want an ibuffer-like buffer for managing tabs.

Currently tab-bar.el contains commands for switching tabs,
not for managing tabs like ibuffer manages buffers.

Since current commands are designed to work like a so-called
"task switcher" that is used in window managers to switch windows,
tab-list was a misnomer.  To reduce confusion I will rename
tab-list to tab-switcher in tab-bar.el.

Then later will create a new ELPA package tab-list.el
that could be developed and used even after Emacs 27 is released,
so its development won't delay the pretest of Emacs 27.

I expect many ibuffer-like features will be implemented in this package,
so it will have the same size as currently the whole tab-bar.el has.

The tab-list.el package could display the tab list using outlines.
For example:

   - Frame 1
    - Tab 1.1
      - Buffer 1.1.1   Size Mode Filename
      - Buffer 1.1.2   Size Mode Filename
    - Tab 1.2
      - Buffer 1.2.1   Size Mode Filename
      - Buffer 1.2.2   Size Mode Filename
      - Buffer 1.2.3   Size Mode Filename
D  - Frame 2
D   - Tab 2.1
      - Buffer 2.1.1   Size Mode Filename
D     - Buffer 2.1.2   Size Mode Filename
    - Tab 2.2
 *%   - Buffer 2.2.1   Size Mode Filename
 *%   - Buffer 2.2.2   Size Mode Filename
>*%   - Buffer 2.2.3   Size Mode Filename

where typing

RET on the frame line will select that frame;
RET on the tab line will switch to that tab;
RET on the buffer line will switch to that tab
    and select window with that buffer;

D x on the frame line will delete that frame;
D x on the tab line will close that tab;
D x on the buffer line will kill that buffer;

C-k or M-w will put the tab into the kill-ring;
C-y would yank the killed tab to another frame
    (when point is moved to another frame line)

Possibilities are endless...