This issue has been around for quite a while Rated 4 out of 5 stars

quote "Version 1.6.8 Released February 9, 2012 87.0 KB Works with Firefox 4.0 - 12.*
x Fixed bug: 'Scroll to Top', 'Scroll to Bottom', 'Page Up', 'Page Down' commands sometimes don't work."

OK, You've got me. 'Scroll to Top', 'Scroll to Bottom' -- These still don't work, even in this page itself!

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