var lastSubMenuID;

       function doRecord(subMenuID) {
              document.getElementById(subMenuID).style.display = "none";
              lastSubMenuID = subMenuID;
       }
       

       function hideLastSubMenu() {
              if(lastSubMenuID == undefined || lastSubMenuID == "") {
                     return;
              } else {
                     var lastSubMenu = document.getElementById(lastSubMenuID);
                     lastSubMenu.style.display = "none";
              }
       }
       

       function showSubMenu(subMenuID) {
              if(lastSubMenuID == subMenuID) {
                     if(document.getElementById(lastSubMenuID).style.display == "block") {
                            document.getElementById(lastSubMenuID).style.display = "none";
                            return;
                     }
              }
              
              if(lastSubMenuID == undefined) {
                     doRecord(subMenuID);
              }else{
                     hideLastSubMenu();
                     doRecord(subMenuID);
              }
              changeMenuState(subMenuID);
       }
       

       function changeMenuState(subMenuID) {
              var subMenu = document.getElementById(subMenuID);
              subMenu.style.display = "block";
       }