Hi,

when the system clipboard has no owner, PGTK Emacs repeatedly shows
assertion warnings, like

(emacs:8121): GLib-GObject-CRITICAL **: 11:28:16.784:
g_object_get_qdata: assertion 'G_IS_OBJECT (object)' failed

The attached trivial one-liner fixes this.
-- 
Jindrich Makovicka