Re: [PATCH] frame.c: focus hooks

[Brian Jenkins <brian@brianjenkins.org>]

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Hi, Drew.

Thanks for the feedback.

Unfortunately, no.  The "focus in" and "focus out" events in Emacs fire
per frame.  So alt-tabbing between Emacs frames will trigger a focus loss
event for the origin frame and focus gain for the destination frame

Initially I tried hacking in at the terminal level (nsterm.c, xterm.c,
and w32term.c) but I had difficulty figuring out how application
(opposed to frame) focus works under X.  It's not clear to me that X
itself even *has* a concept of "active application" distinct from "frame
that has input focus".  (Perhaps this concept exists at the window
manager level, but there are a lot of window managers...) I'm not even a
beginner at X programming, though, so maybe someone could point me in
the right direction?

The convenient thing about patching into the "focus in" and "focus out"
events is that they live up in frame.c, which appears to be
cross-platform.

Best,
Brian


On Sun, Nov 17, 2013 at 5:33 PM, Drew Adams <drew.adams@oracle.com> wrote:

> > I'd like to contribute the attached patch, which adds hooks into
> > gain and loss of focus events.
> >
> > This allows saving all buffers on loss of focus.  (Alt-tabbing
> > between an editor and browser is a popular workflow for web
> > programmers.)
> >
> > It also allows reversion of buffers on regain of focus, convenient
> > if one is switching between Emacs and another editor.
> >
> > People will probably find other handy uses for these hooks.
>
> Sounds useful.
>
> Is this only for a focus switch between Emacs (any frame) and some
> other application?  Or is it also for a focus switch from one Emacs
> frame to another.
>
> (I hope it is the former, which is what you describe in your example
> use cases.)
>

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