[gnome-boxes] app: Withdraw system notifications on exit

[Felipe Borges <felipeborges src gnome org>]

commit d6e52944721c31b4031a70b03b0bc459d010f137
Author: Felipe Borges <felipeborges gnome org>
Date:   Tue Dec 13 20:29:01 2016 +0100

    app: Withdraw system notifications on exit
    
    This patch keeps track of the system notifications as they appear
    and withdraws them when the application quits.
    
    The HIG[0] says that "Notifications in GNOME 3 persist after they
    have been initially displayed. It is therefore important to remove
    notification messages that are no longer relevant to the user."
    
    [0] https://developer.gnome.org/hig/stable/notifications.html.en
    
    https://bugzilla.gnome.org/show_bug.cgi?id=776058

 src/app.vala |   14 +++++++++++++-
 1 files changed, 13 insertions(+), 1 deletions(-)
---
diff --git a/src/app.vala b/src/app.vala
index 71fe097..eed58c8 100644
--- a/src/app.vala
+++ b/src/app.vala
@@ -21,6 +21,7 @@ private class Boxes.App: Gtk.Application {
     public const string DEFAULT_SOURCE_NAME = "QEMU Session";
 
     private List<Boxes.AppWindow> windows;
+    private List<string> system_notifications;
 
     public unowned AppWindow main_window {
         get { return (windows.length () > 0) ? windows.data : null; }
@@ -48,6 +49,7 @@ private class Boxes.App: Gtk.Application {
         app = this;
         async_launcher = AsyncLauncher.get_default ();
         windows = new List<Boxes.AppWindow> ();
+        system_notifications = new List<string> ();
         sources = new HashTable<string,CollectionSource> (str_hash, str_equal);
         brokers = new HashTable<string,Broker> (str_hash, str_equal);
         var action = new GLib.SimpleAction ("quit", null);
@@ -289,6 +291,10 @@ private class Boxes.App: Gtk.Application {
         }
         async_launcher.await_all ();
         suspend_machines ();
+
+        // Withdraw all the existing notifications
+        foreach (var notification in system_notifications)
+            withdraw_notification (notification);
     }
 
     public void open_name (string name) {
@@ -436,6 +442,12 @@ private class Boxes.App: Gtk.Application {
         assert (default_connection != null);
     }
 
+    private new void send_notification (string notification_id, GLib.Notification notification) {
+        base.send_notification (notification_id, notification);
+
+        system_notifications.append (notification_id);
+    }
+
     public void notify_machine_installed (Machine machine) {
         if (machine.window.is_active) {
             debug ("Window is focused, no need for system notification");
@@ -447,7 +459,7 @@ private class Boxes.App: Gtk.Application {
         var notification = new GLib.Notification (msg);
         notification.add_button ("Launch", "app.launch-box::" + machine.name);
 
-        send_notification (null, notification);
+        send_notification ("installed-" + machine.name, notification);
     }
 
     private async void setup_sources () {