visit/unvisit links produces an error Rated 4 out of 5 stars

in Fx13, WD1.1.9 clicking the visit/unvisit link under miscellaneous produces the error:

Timestamp: 5/26/2012 7:24:55 PM
Error: Components.classes['@mozilla.org/browser/global-history;1'] is undefined
Source File: chrome://webdeveloper/content/common/history.js
Line: 7

This review is for a previous version of the add-on (1.1.9).