b=623380 destroy XtClient child window on unrealize r=stransky

--HG--
extra : transplant_source : u%8A%02%E1%C5%96%16%21ica%9A%80%AF%A3e%16%0C%7Dy

widget/gtkxtbin/gtk2xtbin.c

@@ -619,6 +619,11 @@ xt_client_create ( XtClient* xtclient ,
 void
 xt_client_unrealize ( XtClient* xtclient )
 {
+  /* Explicitly destroy the child_widget window because this is actually a
+     child of the socket window.  It is not a child of top_widget's window
+     when that is destroyed. */
+  XtUnrealizeWidget(xtclient->child_widget);
+
 #if XlibSpecificationRelease >= 6
   XtUnregisterDrawable(xtclient->xtdisplay,
                        xtclient->top_widget->core.window);