Re: What improvements would be truly useful?

[Daniel Colascione]

On 03/08/2018 08:24 AM, Alan Third wrote:
> On Thu, Mar 08, 2018 at 03:20:58PM +0200, Eli Zaretskii wrote:
> > > From: Philipp Stephani <address@hidden>
> > > Date: Wed, 07 Mar 2018 21:45:46 +0000
> > > Cc: Daniele Nicolodi <address@hidden>, address@hidden
> > >
> > > By adding a gtkterm.c, that does the same as w32term.c, just for GTK, without 
> > > referring to X.org in any way?
> > > The cleanup would then consist in removing all GTK functionality from xterm.c 
> > > once gtkterm.c is stable.
> >
> > (I guess you meant removing GTK-related portions of xfns.c as well?)
> >
> > If you look at these two files, you will see that the GTK-specific
> > snippets in them are a few and far between.  Most of the code is
> > generic.
>
> That’s part of the problem with how Emacs deals with GTK, it does many
> things the X way rather than the GTK way.
>
> For example, mouse and keyboard events are dealt with using X code,
> but GTK provides it’s own APIs for dealing with them. I thought
> implementing touch events would be easy because GTK already does all
> the heavy lifting, but Emacs doesn’t use GTK for events.
>
> I strongly suspect a Wayland compatible GTK Emacs would have to remove
> a lot of (all?) X code and replace it with GTK code.
>
> > My understanding of this sub-thread was that the idea was to separate
> > GTK _architecturally_, not just making it yet another display
> > back-end.
>
> I don’t think I understand the difference.

Emacs can be compiled with support for many different window systems, 
such as X11, MS-Windows, and Cocoa/NS. Currently, having chosen the X11 
window system, you can go on to choose which toolkit you want to use: 
Motif, GTK2, GTK3, Lucid, and so on.

The proposal is to promote GTK support from an X11 toolkit to a 
top-level window system, excising, in the process, the GTK display 
back-end of any mention of X11.

I think it's an excellent project and one important to the future 
maintainability of the project. As much as it saddens* me to say so, X11 
is dying, while GTK will continue to be a decent abstraction that will 
hit the happy, conventional path of GNU/Linux input and display 
infrastructure. Emacs X11 integration being unusual and dubiously legal 
has caused compatibility problems in the past, particularly with systems 
like NX.

As part of this effort, I'd love to see more abstraction in the window 
system selection. All the xterm.c functions that we carefully replicate 
in every window system really should be a table of frame-specific 
function pointers, and we should be able to compile a single Emacs 
binary with support for all window systems enabled simultaneously.

* IMHO, Wayland should be been a series of new X protocol extensions, 
not a greenfield project.