https://bugs.kde.org/show_bug.cgi?id=305136
nyanpasu64 <nyanpas...@tuta.io> changed:
What |Removed |Added
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CC| |nyanpas...@tuta.io
--- Comment #9 from nyanpasu64 <nyanpas...@tuta.io> ---
I was planning to file this bug myself, but found this bug report, so I'll post
my investigation here.
SUMMARY
When using GTK apps like Firefox in a KDE desktop, files open in the wrong apps
compared to in KDE.
STEPS TO REPRODUCE
1. Install KDE on a Linux distro.
2. xdg-mime query default image/png
3. gio mime image/png
OBSERVED RESULT
xdg-mime (delegating to ktraderclient5) matches file associations in Qt/KDE
apps, and picks reasonable default apps (based on the InitialPreference values
in .desktop files).
gio mime matches file associations in GTK apps or Firefox, and picks
unreasonable default apps, like opening images in gimp.desktop or
okularApplication_kimgio.desktop instead of org.kde.gwenview.desktop. (This is
approximately alphabetically sorted, and matches the order in
/usr/share/applications/mimeinfo.cache.)
EXPECTED RESULT
In a desktop configured by KDE, gio mime should match file associations in KDE
apps, and have reasonable defaults.
SOFTWARE/OS VERSIONS
Operating System: Arch Linux
KDE Plasma Version: 5.21.90
KDE Frameworks Version: 5.82.0
Qt Version: 5.15.2
Kernel Version: 5.12.7-arch1-1 (64-bit)
Graphics Platform: X11
Processors: 12 × AMD Ryzen 5 5600X 6-Core Processor
Memory: 15.6 GiB of RAM
Graphics Processor: NVIDIA GeForce GT 730/PCIe/SSE2
ADDITIONAL INFORMATION
This issue was already analyzed 7 years ago in the Firefox bug tracker, at
https://bugzilla.mozilla.org/show_bug.cgi?id=727422#c24.
To summarize/elaborate, KDE extends the .desktop file spec with KDE-specific
keys. For example, apps can specify InitialPreference (a default priority)
which KDE (and only KDE to my knowledge) uses to pick default apps, if the user
doesn't override the order through ~/.config/mimeapps.list (or
/etc/xdg/mimeapps.list or /usr/share/mime/mimeapps.list). As a result, when
opening files in KDE, KDE apps (the only ones to specify InitialPreference) are
picked first ahead of other apps by default. For example,
/usr/share/applications/org.kde.gwenview.desktop has InitialPreference=8. GNOME
apps (which use glib's g_app_info_get_all_for_type/etc.) do not use these
priorities, so opening downloaded files in Firefox defaults to mimeinfo.cache
(which is usually in alphabetical order, which is not what you generally want).
I think KDE should export the InitialPreference values to mimeapps.list. But
the exact design involves multiple decisions that trade-off between multiple
desired/undesired properties. One decision is choosing whether to install to
/usr/share/applications/ (overriden by /etc/xdg/mimeapps.list) or ~/.config/
(can't be overriden except by per-user config). Another is how to handle
mismatches between the .desktop files and mimeapps.list; we need to handle both
adding/removing applications or packages changing InitialPreference, and the
user editing mimeapps.list (though perhaps users shouldn't be editing
/usr/share/applications/ when /etc/xdg/ is a cleaner way to override it?). Yet
another is choosing whether to write mimeapps.list or KDE-mimeapps.list.
/etc/xdg/mimeapps.list seems to work on both GNOME and KDE. However I ran into
some roadblocks while setting it up. I tried copying my own mimeapps.list to
/etc/xdg/mimeapps.list (then renaming my own to deactivate it), but forgot to
`chmod 644 /etc/xdg/mimeapps.list` before testing MIME lookup. Apparently KDE
apparently "cached" that that file was inaccessible, and didn't use it even
after I ran `chmod 644 /etc/xdg/mimeapps.list` and `update-desktop-database
/etc/xdg`, until I deleted and recreated mimeapps.list.
An alternative to exporting preferences to mimeapps.list (which can be read by
update-desktop-database) is extending or rewriting update-desktop-database to
use InitialPreference values when generating mimeinfo.cache files.
Yet another alternative is to tell glib to add support for InitialPreference
values ;). Though I don't know how GNOME supports default apps, or reordering
apps system-wide or on a per-user level (I assume per-user reordering is done
through ~/.config/mimeapps.list). Does GNOME allow setting one app above
another for *every* file that both can handle? I wish KDE allowed for that, but
I don't think it's possible without editing /usr/share/applications/ and hoping
it doesn't get overwritten in a package update.
I'm going to be experimenting with writing a daemon or tool of my own, to test
various approaches to generating mimeapps.list or mimeinfo.cache. If anyone is
interested in my efforts, or wants to do something similar "officially" in the
KDE or XDG projects, let me know!
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