On 'Back' button of browser, drop down doesn't get refreshed

Hey guys,

i have a drop down in my UI, which value gets filled by session[:sale].

<%= select_tag :sale_id, options_for_select([["Select Sale", "0"]] + @sales.collect { |s| [s.name, s.name] }, selected = session[:saleid]), { :id => "sale_id", :onchange => "search_verify();" } %>

I have a post on, 'onchange' event of it. if i have selected sale1, the item list will come of sale1. Then i selected sale2, sale2 list will be there. Now i clicked 'Back' button of browser, the list gets changed to sale1's items list but in drop down, still it shows sale2 rather than sale1. Now when i click again on 'Back' button of browser, it shows no items list and sale1 in drop down. It seems like drop down goes one step back to the items list.

Please give any soltion to control on Browser Back button or session related any idea.

Thanks in advance!