function newImage(arg) {
  if (document.images) {
    rslt = new Image();
    rslt.src = arg;
    return rslt;
  }
}

function changeImages() {
  if (document.images && (preloadFlag == true)) {
    for (var i=0; i<changeImages.arguments.length; i+=2) {
      document[changeImages.arguments[i]].src = changeImages.arguments[i+1];
    }
  }
}

var preloadFlag = false;
function preloadImages() {
  if (document.images) {
    menu_left_find_over = newImage("imgs/menu_left_find_over.gif");
    
    menu_top_a_1_over = newImage("imgs/menu_top_a_1_over.gif");
    menu_top_a_2_over = newImage("imgs/menu_top_a_2_over.gif");
    menu_top_a_3_over = newImage("imgs/menu_top_a_3_over.gif");
    menu_top_a_4_over = newImage("imgs/menu_top_a_4_over.gif");
    menu_top_a_5_over = newImage("imgs/menu_top_a_5_over.gif");
    menu_top_a_6_over = newImage("imgs/menu_top_a_6_over.gif");
    menu_left_operation_1_1_over = newImage("imgs/menu_left_operation_1_1_over.gif");
    menu_left_operation_1_2_over = newImage("imgs/menu_left_operation_1_2_over.gif");
    menu_left_operation_2_1_over = newImage("imgs/menu_left_operation_2_1_over.gif");
    menu_left_operation_2_2_over = newImage("imgs/menu_left_operation_2_2_over.gif");
    menu_left_operation_3_1_over = newImage("imgs/menu_left_operation_3_1_over.gif");
    menu_left_operation_3_2_over = newImage("imgs/menu_left_operation_3_2_over.gif");
    menu_left_operation_4_1_over = newImage("imgs/menu_left_operation_4_1_over.gif");
    menu_left_operation_4_2_over = newImage("imgs/menu_left_operation_4_2_over.gif");
    menu_left_operation_5_1_over = newImage("imgs/menu_left_operation_5_1_over.gif");
    menu_left_operation_5_2_over = newImage("imgs/menu_left_operation_5_2_over.gif");
   
    menu_left_option_2_over = newImage("imgs/menu_left_option_2_over.gif");
   
    preloadFlag = true;
  }
}