Index: branches/5.1.x/core/admin_templates/js/script.js
===================================================================
diff -u -N -r13402 -r13461
--- branches/5.1.x/core/admin_templates/js/script.js	(.../script.js)	(revision 13402)
+++ branches/5.1.x/core/admin_templates/js/script.js	(.../script.js)	(revision 13461)
@@ -1795,4 +1795,34 @@
 			break;
 		}
 	}
+}
+
+function disable_categories($category_dropdown_id, $allowed_categories) {
+    if ($allowed_categories === true) {
+    	return ;
+    }
+
+	var $selected_category = false;
+	var $categories = $( jq('#' + $category_dropdown_id) ).children('option');
+
+    $categories.each(
+    	function () {
+    		var $me = $(this);
+    		var $category_id = parseInt( $me.attr('value') );
+
+    		if (!in_array($category_id, $allowed_categories)) {
+    			if ($me.attr('selected')) {
+    				$selected_category = $me;
+    			}
+
+    			$me.attr('disabled', 'disabled');
+    		}
+    	}
+    );
+
+    if ($selected_category !== false && $allowed_categories.length > 0) {
+    	// when selected category became disabled -> select 1st available category
+    	$selected_category.attr('selected', '');
+    	$("option[value='" + $allowed_categories[0] + '"]', $categories).attr('selected', 'selected');
+    }
 }
\ No newline at end of file