Fixed segfault when displaying notification + new monitor is mapped

src/main.vala

@@ -146,6 +146,7 @@ namespace SwayNotificationCenter {
             notifications_widget = new Widgets.Notifications ();
             control_center = new ControlCenter ();
 
+            add_window (floating_notifications);
             add_window (control_center);
 
             noti_daemon.on_dnd_toggle.connect ((dnd) => {

src/notificationWindow/notificationWindow.vala

@@ -46,11 +46,6 @@ namespace SwayNotificationCenter {
             });
             this.unmap.connect (() => {
                 debug ("NotificationWindow un-mapped");
-
-                // Destroy the wl_surface to get a new "enter-monitor" signal and
-                // fixes issues where keyboard shortcuts stop working after clearing
-                // all notifications.
-                ((Gtk.Widget) this).unrealize ();
             });
 
             // TODO: Make option
@@ -303,6 +298,13 @@ namespace SwayNotificationCenter {
                 }
             }
 
+            if (!visible) {
+                // Destroy the wl_surface to get a new "enter-monitor" signal and
+                // fixes issues where keyboard shortcuts stop working after clearing
+                // all notifications.
+                ((Gtk.Widget) this).unrealize ();
+            }
+
             set_visible (true);
 
             list.append.begin (noti);