Hi,
> In that case, could you explain in more detail what zoom.el attempts
> to do
Zoom (
https://github.com/cyrus-and/zoom) aims to enforce a fixed window layout so that the selected window is always *big enough*. I think the screencast at the project page is quite clear about the usage.
The implementation is very simple, every time a window change is *detected* the following happens:
1. `balance-windows` is called;
2. the selected window is resized.
This, in practice, has the effect of disabling the manual resizing of windows.
The problem is that to implement the "every time a window change is detected" part I currently hook several functions, specifically:
(add-hook 'window-size-change-functions #'zoom--handler)
(advice-add #'select-window :after #'zoom--handler)
This is clearly an hack-ish solution but Zoom works fairly well most of the times. On the other thread Martin suggested to replace `advice-add` with an hook to `buffer-list-update-hook`, but the main issue remains that `zoom--handler` actually resizes windows in the `window-size-change-functions` hook.
Moreover, this solution causes the handler to be called several times and most of them are useless. (Additional guards can be added but still...)
> and what does it need from Emacs core to be able to do that?
My knowledge of the Emacs internals is quite limited but at the highest level of abstraction what AFAIK is missing is a way to enforce custom window layouts and manage the windows size. This part seems quite fragile / extremely hard to work with (just look at the implementation of `balance-windows`). In addition to that there are some features that further complicate the situation, e.g., side windows and not resizable windows.
Said that, I'm definitely not in a position to make any feature requests but I would appreciate any feedback or suggestions.
Thanks,
Andrea