On Fri, 19 Sep 2025 at 13:00:23 +0300, Martin-Éric Racine wrote:
pe 19.9.2025 klo 12.55 Simon McVittie ([email protected]) kirjoitti:
The gnome-session-common in experimental already prefers Papers, but I
don't think we're ready to release that to unstable yet.
The reason I say this is because of the upstream code in gnome-session
(which is entangled with components like gnome-shell and gdm), rather
than because of the MIME apps list. It would be fine to prefer Papers
with higher priority than Evince in unstable.
In stable, I think it would be more appropriate (certainly more
conservative) to prefer Evince as higher priority than Papers, while
still preferring Papers as higher priority than any other random app
that happens to be able to open PDFs, such as GIMP.
Stable/Unstable don't have to prefer the new apps. They merely have to
acknowledge that Papers is a valid app for the same MIME types as
Evince and Showtime for the same ones as Totem.
This is not about what is or is not a valid MIME handler. Whether Papers
is a valid MIME handler for PDFs *is* under Papers' control (it's part
of the .desktop file) and this is done correctly. mimeapps.list is about
what the desktop environment prefers as a reasonable default. The only
thing that can be done to make Papers a higher-priority PDF reader than
GIMP is for the desktop environment to say that it prefers Papers > GIMP
(in practice either Papers > Evince > other or Evince > Papers > other).
The problem is that Evince, Papers and GIMP all declare that they are
valid PDF handlers, and in the absence of any information about which
one to prefer, the desktop environment infrastructure will chose one
essentially at random. I suspect it might be as simple as GIMP coming
before Papers in alphabetical order, or perhaps gimp.desktop before
org.gnome.Papers.desktop.
This is particularly visible for GIMP because nobody *actually* wants
GIMP to be their default PDF reader (#525077, #759704), but it is
completely true that it can read PDFs (therefore correct to list it as a
MimeType), and there is no mechanism to mark a viewer/reader as
less-preferred than others, only more-preferred.
Ideally there would be a way for GIMP to say "yes technically I can open
PDFs, but it's never appropriate for this to be the default", so that
random other PDF readers like xpdf would always "win" vs. GIMP; but there
is currently no such mechanism in the freedesktop.org specifications
(https://gitlab.freedesktop.org/xdg/xdg-specs/-/issues/219,
https://gitlab.freedesktop.org/xdg/xdg-specs/-/issues/43) and until such
a mechanism exists, it is not possible for GIMP to declare that it
supports PDFs without it sometimes becoming the default.
smcv
