Set layershell namespace for blankwindows

src/blankWindow/blankWindow.vala

@@ -38,6 +38,7 @@ namespace SwayNotificationCenter {
                 Process.exit (1);
             }
             GtkLayerShell.init_for_window (this);
+            GtkLayerShell.set_namespace (this, "swaync-control-center");
             GtkLayerShell.set_monitor (this, monitor);
 
             GtkLayerShell.set_anchor (this, GtkLayerShell.Edge.TOP, true);