Ludovic Courtès <ludo@gnu.org> skribis:

> This is not news to us, but as
> <https://distrowatch.com/weekly.php?issue=20190624#guixsd> notes, the
> application menu of desktop environments is not automatically updated
> when a package is installed or removed.  It’d be great if we could
> somehow notify the desktop environment.

We’ve investigated today on IRC with Maxim and Leo P. and here’s the
summary of our findings:

  • GNOME Shell, in ‘appDisplay.js’, “listens” to the
    ‘installed-changed’ GLib signals and uses that to rebuild its
    application menu.

  • In ‘shell-app-system.c’, ‘installed-changed’ is emitted when the
    GAppInfoMonitor emits ‘changed’:

      monitor = g_app_info_monitor_get ();
      g_signal_connect (monitor, "changed", G_CALLBACK (installed_changed), self);
      installed_changed (monitor, self);

  • GLib emits the ‘changed’ signal when ‘g_app_info_monitor_fire’ is
    called from ‘desktop_file_dir_changed’, itself called when one of
    the directories in $XDG_DATA_DIRS (among others) changes.  It uses
    ‘GFileMonitor’ under the hood, which is essentially inotify.

The GLib patch below is an attempt to monitor ~/.guix-profile and to
treat changes to that symlink as if they were changes to
~/.guix-profile/share/applications (which contains ‘.desktop’ files.)
It actually builds but I haven’t tested it yet.  :-)

WDYT?

If we take that route, we could add a ‘replacement’ for GLib.

Thanks,
Ludo’.