Subject: Re: bug#62592: Not creating new Tabs with small window

From: martin rudalics <[email-masked]>
Date: Wed, 17 May 2023 09:07:21 +0200

>>>> 1. ~ $ emacs -Q
 >>>> 2. Menu -> Options -> Show/Hide -> Tab Bar (gives Tab *scratch*)
 >>>> 3. resize the Emacs window to a small one, but large enough to show some Tab labels
 >>>> 3. 1x click on rightmost * in the Tab Bar to create a new Tab
 >>>>
 >>>> The bug: No new Tab will be created and the minibuf and*Messages*  show:
 >>>>
 >>>>     split-window: Window #<window 3 on*Messages*> too small for splitting
 >>>
 >>> Thanks for the bug report.  It is related to bug#62427 where
 >>> we need to find a way to create a new window without using
 >>> delete-windows and split-window.
 >
 > The patch below still fails when the height of the window is 1 line.
 >
 > Maybe Martin could help?
 >
 >> diff --git a/lisp/tab-bar.el b/lisp/tab-bar.el
 >> index 35474e1c674..08f904ec73d 100644
 >> --- a/lisp/tab-bar.el
 >> +++ b/lisp/tab-bar.el
 >> @@ -1586,7 +1595,8 @@ tab-bar-new-tab-to
 >>                 (window-state-put (window-state-get))
 >>               ;; Create a new window to get rid of old window parameters
 >>               ;; (e.g. prev/next buffers) of old window.
 >> -            (split-window) (delete-window))))
 >> +            (let ((window-min-height 1)) (split-window))
 >> +            (delete-window))))
 >>
 >>         (let ((buffer
 >>                (if (and (functionp tab-bar-new-tab-choice)
 >> diff --git a/lisp/window.el b/lisp/window.el
 >> index aa7520f30fa..b2ee869940a 100644
 >> --- a/lisp/window.el
 >> +++ b/lisp/window.el
 >> @@ -6391,7 +6396,8 @@ window-state-put
 >>                        (selected-window)))
 >>         (delete-other-windows-internal window root)
 >>         ;; Create a new window to replace the existing one.
 >> -      (setq window (prog1 (split-window window)
 >> +      (setq window (prog1 (let ((window-min-height 1))
 >> +                            (split-window window))
 >>                        (delete-window window)))))
 >>
 >>     (set-window-dedicated-p window nil)

Split the window horizontally.  If a user can see the "+" button on the
tab bar, the containing frame should be wide enough to accommodate two
side-by-side windows.  Also it's always better to specify an explicit
SIZE argument to make a small window than to bind 'window-min-height'.

For Emacs 30 I'd recommend a new routine say 'clean-window' to make its
argument window pristine.  The way you do it now loses all overlays with
a window property in the window's buffer.

martin