Sync Wingpanel transparency

src/Cards/UserCard.vala

@@ -360,6 +360,7 @@ public class Greeter.UserCard : Greeter.BaseCard {
         set_keyboard_layouts ();
         set_mouse_touchpad_settings ();
         set_interface_settings ();
+        set_wingpanel_settings ();
         set_night_light_settings ();
         set_power_settings ();
         update_style ();
@@ -457,6 +458,16 @@ public class Greeter.UserCard : Greeter.BaseCard {
         background_settings.set_value ("primary-color", settings_act.primary_color);
     }
 
+    private void set_wingpanel_settings () {
+        var wingpanel_schema = SettingsSchemaSource.get_default ().lookup ("io.elementary.desktop.wingpanel", true);
+        if (wingpanel_schema == null || !wingpanel_schema.has_key ("use-transparency")) {
+            return;
+        }
+
+        var wingpanel_settings = new GLib.Settings ("io.elementary.desktop.wingpanel");
+        wingpanel_settings.set_value ("use-transparency", settings_act.wingpanel_use_transparency);
+    }
+
     private void set_night_light_settings () {
         var night_light_settings = new GLib.Settings ("org.gnome.settings-daemon.plugins.color");
         night_light_settings.set_value ("night-light-enabled", settings_act.night_light_enabled);

src/PantheonAccountsServicePlugin.vala

@@ -65,6 +65,9 @@ interface Pantheon.SettingsDaemon.AccountsService : Object {
     public abstract string monospace_font_name { owned get; set; }
     public abstract bool orientation_lock { get; set; }
 
+    /* Wingpanel */
+    public abstract bool wingpanel_use_transparency { get; set; }
+
     /* Prefer Dark Schedule (part of interface settings)*/
     /* Last coordinates are reused for Night Light settings */
     public abstract Coordinates last_coordinates { get; set; }