var preloadFlag = false;
function preloadImages() {
	if (document.images) {
		pre_top_100_a_over = newImage('images/top_100_a-over.gif');
		pre_top_100_a_down = newImage('images/top_100_a-down.gif');
		pre_topic_a_over = newImage('images/topic_a-over.gif');
		pre_topic_a_down = newImage('images/topic_a-down.gif');
		pre_index_tag_a_over = newImage('images/index_tag_a-over.gif');
		pre_index_tag_a_down = newImage('images/index_tag_a-down.gif');
		pre_partner_a_over = newImage('images/partner_a-over.gif');
		pre_partner_a_down = newImage('images/partner_a-down.gif');
		pre_favorite_a_over = newImage('images/favorite_a-over.gif');
		pre_favorite_a_down = newImage('images/favorite_a-down.gif');
		preloadFlag = true;
	}
}