You'd be surprised how many people use non-GTK X11 Emacs. The reasons they give include being able to connect and disconnect from multiple X servers (GTK has longstanding unfixed bugs here) and being generally lighter on the system than GTK is.

"Pulling [GTK] out into its own frontend" means taking GTK support out of where it is now, Emacs' general-purpose X11 code (where GTK is one of many supported X11 toolkits) and putting it in a new top-level window-system that's a peer of NS (for OS X) and Windows support. The new GTK window system wouldn't be allowed to use X11 functions directly. Under this architecture, Emacs would be much closer to a well-behaved GTK program and could take advantage of cool GTK tricks like Broadway support.

I am one of those X11-only, no-toolkit Emacs users. The only times I need gtk support is when I run a variant build with gtk3 support in order to have a native Wayland window which doesn't require Xwayland. But I primarily use X11 so the no-toolkit, X11-only build.

It does X11 specific calls unconditionally, so it is not currently possible to run emacs as a native Wayland client.

One of the big advantages of the new GTK-only backend I propose in [1] is the ability to use non-X GTK back-ends, like Wayland and Broadway.

But SHTDI. Volunteering?

[1] https://lists.gnu.org/archive/html/emacs-devel/2016-10/msg00...

I already spend most of my day writing an IDE (GNOME Builder) and making it Wayland ready out of the box.

However, I am responsive on #gtk+ answering questions to people working on this.

I'm using a Motif build of emacs. I use mwm too so there is only one toolkit in memory.