var wp_last = "";

function displayWP(idn) {

    if($('span#wp_'+idn).css('display') == "none") {
        if(wp_last != null) displayWP(wp_last);
        $('span#wp_'+idn).show("slow");
        wp_last = idn;

      } else {
        $('span#wp_'+idn).hide("slow");
        wp_last = null;
     }
 
}