This patch adds a "guix gc" button to the low disk space notification
that 'gsd-housekeeping' emits.

diff --git a/plugins/housekeeping/gsd-disk-space.c b/plugins/housekeeping/gsd-disk-space.c
index bd3437e..89027d8 100644
--- a/plugins/housekeeping/gsd-disk-space.c
+++ b/plugins/housekeeping/gsd-disk-space.c
@@ -546,6 +546,21 @@ empty_trash_callback (NotifyNotification *n,
         notify_notification_close (n, NULL);
 }
 
+static void
+guix_gc_callback (NotifyNotification *n,
+                  const char         *action)
+{
+        const gchar *argv[] = { "guix", "gc", NULL };
+
+        g_assert (action != NULL);
+        g_assert (strcmp (action, "run-guix-gc") == 0);
+
+        g_spawn_async (NULL, (gchar **) argv, NULL, G_SPAWN_SEARCH_PATH,
+                       NULL, NULL, NULL, NULL);
+
+        notify_notification_close (n, NULL);
+}
+
 static void
 on_notification_closed (NotifyNotification *n)
 {
@@ -591,6 +606,13 @@ ldsm_notify (const char *summary,
                                                 g_free);
         }
 
+        notify_notification_add_action (notification,
+                                        "run-guix-gc",
+                                        _("Collect Unused Guix Items"),
+                                        (NotifyActionCallback) guix_gc_callback,
+                                        NULL,
+                                        NULL);
+
         has_trash = ldsm_mount_has_trash (mount_path);
 
         if (has_trash) {
ab68b44eef902c46443044'>diff</a></td><td class='form'><form class='right' method='get' action='/guix/log/gnu/packages/tigervnc.scm'>
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<option value='grep'>log msg</option>
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<div class='path'>path: <a href='/guix/log/?id=bf3ea5ec5e57e74f5fab68b44eef902c46443044'>root</a>/<a href='/guix/log/gnu?id=bf3ea5ec5e57e74f5fab68b44eef902c46443044'>gnu</a>/<a href='/guix/log/gnu/packages?id=bf3ea5ec5e57e74f5fab68b44eef902c46443044'>packages</a>/<a href='/guix/log/gnu/packages/tigervnc.scm?id=bf3ea5ec5e57e74f5fab68b44eef902c46443044'>tigervnc.scm</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/gnu/packages/tigervnc.scm?id=bf3ea5ec5e57e74f5fab68b44eef902c46443044&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2019-11-10 12:42:10 +0200'>2019-11-10</span></td><td><a href='/guix/commit/gnu/packages/tigervnc.scm?id=f1d4d79fb3206fa26834b301fae7fc75c7f46ef8'>gnu: Add 'file-name' where appropriate.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/admin.scm (detox, neofetch),
gnu/packages/algebra.scm (python-fpylll),
gnu/packages/bioinformatics.scm (tbsp, genrich),
gnu/packages/crypto.scm (hpenc),
gnu/packages/digest.scm (xxhash),
gnu/packages/emacs-xyz.scm (emacs-tiny, emacs-ergoemacs-mode,
emacs-make-it-so, emacs-poet-theme, emacs-deft, emacs-scribble-mode,
emacs-helm-mu, emacs-unidecode, emacs-diff-hl, emacs-helm-exwm,
emacs-gif-screencast, emacs-exec-path-from-shell),
gnu/packages/engineering.scm (gpx),
gnu/packages/freedesktop.scm (waylandpp),
gnu/packages/golang.scm (go-github-com-sirupsen-logrus,
go-github-com-shirou-gopsutil),
gnu/packages/guile-xyz.scm (guile-studio, guile-picture-language,
jupyter-guile-kernel),
gnu/packages/image-viewers.scm (qview),
gnu/packages/java-maths.scm (java-jblas),
gnu/packages/llvm.scm (libclc),
gnu/packages/logging.scm (spdlog),
gnu/packages/ocaml.scm (ocaml-cstruct, ocaml-zarith),
gnu/packages/terminals.scm (libtsm),
gnu/packages/tigervnc.scm (tigervnc-client),
gnu/packages/xdisorg.scm (xcalib, xbanish) [source]: Add file-name.
</span></span></td><td>Efraim Flashner</td></tr>
<tr><td><span title='2019-10-02 01:27:23 +0200'>2019-10-02</span></td><td><a href='/guix/commit/gnu/packages/tigervnc.scm?id=d8de38563b7a32a96873a8dbc918b6448f3d8665'>gnu: tigervnc-server: Clean up comments.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/tigervnc.scm (tigervnc-server): Clean up comments.
</span></span></td><td>Danny Milosavljevic</td></tr>
<tr><td><span title='2019-10-02 01:24:16 +0200'>2019-10-02</span></td><td><a href='/guix/commit/gnu/packages/tigervnc.scm?id=04784d217a279b22434920ec3054fda1d6ac24ce'>gnu: Add tigervnc-server.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/tigervnc.scm (tigervnc-server): New variable.

Signed-off-by: Danny Milosavljevic &lt;dannym@scratchpost.org&gt;
</span></span></td><td>Todor Kondić</td></tr>
<tr><td><span title='2019-10-02 01:24:09 +0200'>2019-10-02</span></td><td><a href='/guix/commit/gnu/packages/tigervnc.scm?id=0992cfa13aabee70e214057b7343bcb76de77b42'>gnu: Add tigervnc-client.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/tigervnc.scm: New file.
(tigervnc-client): New variable.
* gnu/local.mk (GNU_SYSTEM_MODULES): Add tigervnc.scm.

Signed-off-by: Danny Milosavljevic &lt;dannym@scratchpost.org&gt;
</span></span></td><td>Todor Kondić</td></tr>