Index: wp-admin/js/widgets.dev.js
===================================================================
--- wp-admin/js/widgets.dev.js	(revision 20950)
+++ wp-admin/js/widgets.dev.js	(working copy)
@@ -215,6 +215,11 @@
 		$.post( ajaxurl, data, function(r){
 			var id;
 
+			if ( "0" === r ) {
+				$('img.ajax-feedback', widget).parent().parent().html($('<div class="error">' + widgetsL10n.loggedOut + '</div>'));
+				return false;
+			}
+
 			if ( del ) {
 				if ( !$('input.widget_number', widget).val() ) {
 					id = $('input.widget-id', widget).val();
Index: wp-includes/script-loader.php
===================================================================
--- wp-includes/script-loader.php	(revision 20950)
+++ wp-includes/script-loader.php	(working copy)
@@ -373,6 +373,9 @@
 		$scripts->add( 'admin-gallery', "/wp-admin/js/gallery$suffix.js", array( 'jquery-ui-sortable' ) );
 
 		$scripts->add( 'admin-widgets', "/wp-admin/js/widgets$suffix.js", array( 'jquery-ui-sortable', 'jquery-ui-draggable', 'jquery-ui-droppable' ), false, 1 );
+		$scripts->localize( 'admin-widgets', 'widgetsL10n', array(
+			'loggedOut' => __('You are logged out!')
+		));
 
 		$scripts->add( 'theme', "/wp-admin/js/theme$suffix.js", array( 'jquery' ), false, 1 );