function changeContent(param,ctg){
	var menu = "menu.php?c="+param;
	var link = param+".php";
	if(ctg) {
		var q = "ctg="+ctg;
		menu += '&'+q;
		link += '?'+q;
	}
	parent.content_Frame.document.location = link;
	parent.menu_Frame.document.location = menu;
}
var btn;
function showSwitch(){
	document.write("<IMG src=\"");
	var btn_img = "images/nav/sound_";
	if(parent.sound){
		btn_img+="on";
	}else{
		btn_img+="off";
	}
	btn_img+=".gif";
	document.write(btn_img);
	document.write("\" name=\"soundSwitch\" border=\"0\" />");
	btn = document.soundSwitch;
}
function setBGM(){
	if(parent.sound){
		parent.setSound(false);
		btn.src="images/nav/sound_off.gif";
	}else{
		parent.setSound(true);
		btn.src="images/nav/sound_on.gif";
	}
}