On Fri, Feb 12, 2021 at 3:47 PM Bastian Beranek
<bastian.beischer@gmail.com> wrote:
>
> Hey Juri,
>
> just to let you know, that I've found a problem with my patch on
> text-mode frames. If I create multiple tabs one after another they
> start to appear in a second row and visuals begin to glitch.
>
> I'll try to understand why that is happening.

I found out what the problem was. I had customized
tab-bar-select-tab-modifiers in my .emacs and the :set function of
that variable contained (tab-bar-mode -1) followed by (tab-bar-mode
1). For some reason this caused issues (to reproduce this, apply my
v8.patch, create test.el (as below) and start emacs as follows:

$ cat test.el
(customize-set-variable 'tab-bar-select-tab-modifiers '(super))
(customize-set-variable 'tab-bar-show 1)

$ src/emacs -nw -Q -l test.el
and then create two or more tabs (C-x t 2)

I have now modified the set function to:

diff --git a/lisp/tab-bar.el b/lisp/tab-bar.el
index 87c9fd719d..4e47ae2c10 100644
--- a/lisp/tab-bar.el
+++ b/lisp/tab-bar.el
@@ -89,8 +89,9 @@ tab-bar-select-tab-modifiers
  :set (lambda (sym val)
         (set-default sym val)
         ;; Reenable the tab-bar with new keybindings
-         (tab-bar-mode -1)
-         (tab-bar-mode 1))
+         (when tab-bar-mode
+           (tab-bar-mode -1)
+           (tab-bar-mode 1)))
  :group 'tab-bar
  :version "27.1")

This seems to fix the issue. I can't say I fully understand why
though. It must have something to do with running
tab-bar--update-tab-bar-lines in early initialization? We could also
wrap the call to tab-bar--update-tab-bar-lines.

Please find the full v9 patch attached.

Cheers
Bastian