function imgpreload(){
	files = new Array(
	"http://www.joshi-chat.com/img_parts/menu_top_over.gif",
	"http://www.joshi-chat.com/img_parts/menu_about_over.gif",
	"http://www.joshi-chat.com/img_parts/menu_regist_over.gif",
	"http://www.joshi-chat.com/img_parts/menu_point_over.gif",
	"http://www.joshi-chat.com/img_parts/menu_chat_over.gif",
	"http://www.joshi-chat.com/img_parts/menu_search_over.gif",
	"http://www.joshi-chat.com/img_parts/menu_mymenu_over.gif",
	"http://www.joshi-chat.com/img_parts/menu_faq_over.gif");
	preimgs = new Array();
	for(i=0;i<files.length;i++){
		preimgs[i] = new Image();
		preimgs[i].src = files[i];
	}
}

function chgbtn(btnname,btnno,btntype){
	document.images[btnname].src='http://www.joshi-chat.com/img_parts/'+btnname+btnno+'.'+btntype;	
}