Update Scanner

I find lots of copies of old webpages (pairs of *.new and *.old) which were removed from the scanner's task list a long time ago, with last-modified dates several months old.
 
 
BTW a suggestion:
I really need a quick way to disable UpdateScanner temporarily. To toggle from enabled to disabled by statusbar icon right-click and a red arrow for the disabled state would be great. (for example I'm monitoring addons.mozilla.org which usually works fine, except I'm logged in there. Then several text items on every page change and UpdateScanner is triggered everywhere - but it shouldn't for the time I'm logged in.)