Re: Bug#927667: gnome: please confirm or revert choice of Wayland for default desktop

Dear Simon,

Thanks for taking the time to file this, I had been meaning to in the 
week leading up to Easter but I was unable to get much computer time.

On Sat, Apr 20, 2019 at 08:44:42PM +0100, Simon McVittie wrote:
> but I think it would be good to reassess the costs and benefits
>of Wayland vs. X11 by default, and either make a positive decision to
>keep Wayland as the default, or diverge from upstream and switch back
>to Xorg by default like Debian stretch and Ubuntu 18.04 did.

The decision as to whether GNOME-in-Debian defaults to Wayland or X has
repercussions beyond a GNOME perspective, because GNOME is the default desktop
for Debian. I think the "bar" that must be met for a change of default display
system from X to Wayland for the default Debian desktop is higher than just
for GNOME itself: Debian is a rich ecosystem of thousands of packages from
lots of communities, including GNOME and others; I believe it's a
reasonable expectation of a user that the default desktop system works
reliably with the vast majority of packages within our repositories,
not just those designed specifically for GNOME.

My personal impression of GNOME/Wayland is that it's not up to that standard
just yet (I experience lots of problems when I have tried to evaluate it, but I
have not yet filed nor investigated each of them further, and I should).  But I
would worry about making that judgement myself because I'm not at the cutting
edge of this area. Ubuntu deciding that it wasn't ready for 18.04 was notable
to me; if it wasn't suitable for them, with a narrower focus than Debian, then
I would think it not yet suitable for us either.

What triggered me to say something was learning that some packages were being
autoremoved, with the justification that they don't work well with the (now)
default desktop system. "synaptic" was the first, and a very high profile one
at that (but I think it has now been patched: #818366); another that I became
aware of was "tilde", but I have not performed an exhaustive search and I worry
there may be others. I did try "gparted" to be sure that worked (seems to)
since that's another "best in class" GUI app which was likely to have the same
problems as synaptic.

(I realise that it was neither the GNOME team nor the release team that decided
a package not working under Wayland should be RC, and that you do not
necessarily support that.)

What I would really like to see, please, is pointers to the criteria used in
the decision making for switching to Wayland-for-default. What was considered
important? Is there any consensus with the position I outline in my first
paragraph above? Was this decision made before or after Ubuntu abandoned it for
18.04? Do we know what specific criteria Ubuntu used, and how does it differ to
ours?

>From what I have seen or discovered so far, I argue that GNOME-Wayland is not
yet a suitable choice for the default desktop, and would suggest the simplest
fix would be to revert to GNOME/X11 for Buster and re-evaluate for the next
release.

>(As the maintainer of flatpak in Debian, I would be sad to see us go
>back to a display protocol where every app can copy other apps' window
>contents, inject fake input events or be a keylogger... but I'm also
>aware that some programs rely on X11 not providing meaningful privilege
>separation, and that the Wayland compositor model exacerbates any bugs
>that cause GNOME Shell to crash.)

I can appreciate your position and the improved secure isolation of independent
graphical apps in the Wayland stack is very attractive. I just want to be sure
that we as a project are effectively weighing these new advantages against the
costs. It's important to me that we are not throwing out packages (and the
corresponding work that other developers have put into making Debian as great
as possible), or making the experience of using the wealth of packages within
Debian less seamless for new users, without being aware at a project level that
we are doing it.  I have no axe to grind against Wayland and would never say
"never" to it.


Best wishes