Window focus event

Window focus event

[lxsameer]

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Hey folks,
I was wondering if there is a hook or a way to detect when focus changes from a window to another?

I know about the obsolete `focous-in-hook'. But it seems that its replacement doesn't do the same and works only on frame level. 



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Re: Window focus event

[Michael Heerdegen]

lxsameer <lxsameer@lxsameer.com> writes:

> Hey folks,

Hello.

> I was wondering if there is a hook or a way to detect when focus
> changes from a window to another?
>
> I know about the obsolete `focous-in-hook'. But it seems that its
> replacement doesn't do the same and works only on frame level.

This question would probably better fit and get more attention in
emacs-help.  People seem to be quite busy here ATM.

Regarding the question: I would say `window-configuration-change-hook'
or `window-state-change-hook' are the best fitting hooks for the task.
May depend on your use case.

Note that Emacs sometimes internally selects windows temporarily
(`with-selected-window'), so doing something for every window selection
is most of the time not what you want.

Michael.

Re: Window focus event

[Stefan Monnier]

> Regarding the question: I would say `window-configuration-change-hook'
> or `window-state-change-hook' are the best fitting hooks for the task.
> May depend on your use case.

Indeed.

> Note that Emacs sometimes internally selects windows temporarily
> (`with-selected-window'), so doing something for every window selection
> is most of the time not what you want.

Note that neither of the above two hooks are run during
`with-selected-window`, AFAIK.


        Stefan

Re: Window focus event

[lxsameer]

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‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐

On Thursday, December 16th, 2021 at 3:30 PM, Stefan Monnier <monnier@iro.umontreal.ca> wrote:

> > Regarding the question: I would say `window-configuration-change-hook'
> 

> > or `window-state-change-hook' are the best fitting hooks for the task.
> > 

> > May depend on your use case.
> 

> Indeed.
> 

> > Note that Emacs sometimes internally selects windows temporarily
> > 

> > (`with-selected-window'), so doing something for every window selection
> > 

> > is most of the time not what you want.
> 

> Note that neither of the above two hooks are run during
> 

> `with-selected-window`, AFAIK.
> 

> Stefan

Thanks folks, In the deprecation message of the `focus-in-hook` family, it refers to `after-focus-change-function`. Isn't it better to change that message to include these two hooks as well?

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Re: Window focus event

[Michael Heerdegen]

lxsameer <lxsameer@lxsameer.com> writes:

> Thanks folks, In the deprecation message of the `focus-in-hook`
> family, it refers to `after-focus-change-function`. Isn't it better to
> change that message to include these two hooks as well?

AFAIU, input focus is a per frame concept.  Window selection is
something different.  There are overlaps (the selected window is
typically in the frame that has input focus), but I don't see that
`window-configuration-change-hook' is a replacement for `focus-in-hook'
like `after-focus-change-function' is.

You can change the selected window without changing focus.  It can be
that no frame has input focus.  If a frame gets focus, that doesn't
necessarily change the window configuration, etc.  I hope my mental
model is correct.

Is there anything you could do using `focus-in-hook' that you can't do with
`after-focus-change-function'?

Michael.

Re: Window focus event

[lxsameer]

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Thanks Michael, I think my mental model was wrong. Thanks for the clarification.

‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐

On Friday, December 17th, 2021 at 2:43 PM, Michael Heerdegen <michael_heerdegen@web.de> wrote:

> lxsameer lxsameer@lxsameer.com writes:
> 

> > Thanks folks, In the deprecation message of the `focus-in-hook`
> > 

> > family, it refers to `after-focus-change-function`. Isn't it better to
> > 

> > change that message to include these two hooks as well?
> 

> AFAIU, input focus is a per frame concept. Window selection is
> 

> something different. There are overlaps (the selected window is
> 

> typically in the frame that has input focus), but I don't see that
> 

> `window-configuration-change-hook' is a replacement for` focus-in-hook'
> 

> like `after-focus-change-function' is. You can change the selected window without changing focus. It can be that no frame has input focus. If a frame gets focus, that doesn't necessarily change the window configuration, etc. I hope my mental model is correct. Is there anything you could do using` focus-in-hook' that you can't do with
> 

> `after-focus-change-function'?
> 

> Michael.

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Re: Window focus event

[Stefan Kangas]

lxsameer <lxsameer@lxsameer.com> writes:

> Thanks folks, In the deprecation message of the `focus-in-hook`
> family, it refers to `after-focus-change-function`. Isn't it better to
> change that message to include these two hooks as well?

See also Bug#51862.