As reported here: http://forum.dokuwiki.org/thread/6927
"when I click on edit and the text area appears, the cursor is now at the end of the text. Given that I usually start at the beginning when I edit a text, it's very annoying and disorientating. I have to scroll up each and every time. The behavior started when I installed Firefox 4 (4.0/Mac) and so far I haven't found a solution online."