if(document.images){
	mtx = new Image(); mtx.src = "../common_files/main_topicx.gif";
	_omtx = new Image(); _omtx.src = "../common_files/_over_main_topicx.gif";

	st = new Image(); st.src = "../common_files/sub_topicx.gif";
	_ost = new Image(); _ost.src = "../common_files/_over_sub_topicx.gif";
	
	aa = new Image(); aa.src = "../common_files/arrow_white.gif";
	_oaa = new Image(); _oaa.src = "../common_files/arrow_blue.gif";
}