We had been using href=foo for leftNav links instead of href=# because screenreaders read <a href=#…> as “link this page” and that may mislead SR users to tab around looking for the content. (The real action of clicking is to submit a form via an onclick.)
But we have to use href=# because otherwise IE fires onbeforeunload once because href!=# and once because the onclick causes a nav change (because it calls submit() on a form). We can’t use setTimeout to ignore the 2nd firing because we need the form submission to happen, and we can’t skip the 1st firing because we need it when the user clicks a non-link (such as form buttons and the window ‘X’ close button).
So, we have to live with the screenreader (JAWS) behavior of reading these links as “link this page”.