Context: GNU Emacs 29.0.60 (build 1, x86_64-pc-linux-gnu, X toolkit, cairo version 1.16.0, Xaw3d scroll bars) of 2023-03-30, Development version 4508a024e818 on emacs-29 branch; build date 2023-03-30. Linux Mint 21 (Vanessa) Cinnamon: ~ $ emacs -Q .

Trying to create a new Tab in the Tab Bar I am getting a message about not being able to split a Window:

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What does Window mean in this message? I ask for a new Tab and not for splitting a Window.

The described behavior is the same no matter in which way creating a new Tab was requested. So both, clicking the rightmost + in the Tab-Bar and choosing 'New Tab' from File-Menu give the same outcome.

  • Could you add to your question how you are trying to create the new tab? Commented Apr 2, 2023 at 12:06
  • 1
    @dalanicolai : thanks for the hint towards a detail I should mention in my question. I have edited my question and it is now there.
    – oOosys
    Commented Apr 2, 2023 at 12:18
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    Anyway, when creating a new tab, the function tab-bar-new-tab-to gets called, which uses split-window (so it seems that creating the new tab, normally, requires splitting a window). Then the message means what it says: that your window is too small to create another window. So it should work when you use a window that is large enough. Otherwise, maybe you can make it work by adjusting the window-min-height/width values. It seems that you can use the window-min-size to find out the 'minimum size limits'. Commented Apr 2, 2023 at 12:23
  • @dalanicolai : see my answer for my current point of view on this issue. Feel free to point out if something in that answer is not correct. And yes, I am aware of the work-around you mention. To get the tab created is not what I am after. What I am after is understanding why it is how it is as in my eyes it is not the way it should be.
    – oOosys
    Commented Apr 2, 2023 at 16:04

1 Answer 1

What does "split-window: Window #<window 3 on scratch> too small for splitting" mean?

This quite misleading message is the result of not well defined concept of what a Tab Bar and the Tabs in the Tab Bar actually are.

It exposes messing around with concepts you can experience reading the Emacs documentation or the actual code if paying enough attention to the very detail and the correctness of used wording.

This mess is the result of mixed and ambiguous use of the concepts 'frame', 'window', 'root window', 'window configuration' and 'tab' to a degree where it is no more possible to describe parts of Emacs GUI with unambiguous wording.

Let's nail down this above to the case of creating a New Tab:

When creating a new Tab, the function tab-bar-new-tab-to gets called, which in turn calls split-window. Instead of duplication of the elisp "object" behind the Tab or just creation of an "empty" Tab object some kind of workaround is used and leads then to the observed confusing side-effect.

In other words the error message means that a window in the Tab is too small to be split in the vertical direction exposing a design-flaw in the mechanism used to create a new Tab.

Check out in this context: bugreport bug=62592

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