cinnamon-gtk-embed: Clamp transparency of the tray icon's underlying

MetaWindowActor.

Fixes #10830

Author: mtwebster

src/cinnamon-gtk-embed.c

@@ -57,6 +57,17 @@ cinnamon_gtk_embed_remove_window_actor (CinnamonGtkEmbed *embed)
   clutter_clone_set_source (CLUTTER_CLONE (embed), NULL);
 }
 
+static void
+maintain_transparency (ClutterActor *actor,
+                       GParamSpec *pspec,
+                       gpointer user_data)
+{
+    if (clutter_actor_get_opacity (actor) != 0) {
+        g_signal_stop_emission_by_name (actor, "notify::opacity");
+        g_object_set (actor, "opacity", 0, NULL);
+    }
+}
+
 static void
 cinnamon_gtk_embed_window_created_cb (MetaDisplay   *display,
                                    MetaWindow    *window,
@@ -93,6 +104,7 @@ cinnamon_gtk_embed_window_created_cb (MetaDisplay   *display,
       /* Hide the original actor otherwise it will appear in the scene
          as a normal window */
       clutter_actor_set_opacity (window_actor, 0);
+      g_signal_connect (window_actor, "notify::opacity", G_CALLBACK (maintain_transparency), NULL);
 
       /* Also make sure it (or any of its children) doesn't block
          events on wayland */