https://bugs.gentoo.org/919092
https://github.com/lxde/lxpanel/commit/0853b0fc981285ebd2ac52f8dfc2a09b1090748c

From 0853b0fc981285ebd2ac52f8dfc2a09b1090748c Mon Sep 17 00:00:00 2001
From: Ravi Kant Sharma <600723+raviksharma@users.noreply.github.com>
Date: Tue, 30 Jul 2024 17:52:07 +0200
Subject: [PATCH] Fix gcc-14 build error

gcc-14 now treats a conversion between pointers of incompatible types
as an error.
--- a/plugins/tray.c
+++ b/plugins/tray.c
@@ -631,7 +631,7 @@ static GtkWidget *tray_constructor(LXPanel *panel, config_setting_t *settings)
     /* Add GDK event filter. */
     gdk_window_add_filter(NULL, (GdkFilterFunc) tray_event_filter, tr);
     /* Reference the window since it is never added to a container. */
-    tr->invisible = g_object_ref_sink(G_OBJECT(invisible));
+    tr->invisible = GTK_WIDGET(g_object_ref_sink(G_OBJECT(invisible)));
     tr->invisible_window = GDK_WINDOW_XID(gtk_widget_get_window(invisible));
 
     /* Allocate top level widget and set into Plugin widget pointer. */