/**
 * À̹ÌÁö ¸¶¿ì½º ·Ñ¿À¹ö ÇÔ¼öÀÔ´Ï´Ù.
 * ½ÇÁ¦ »ç¿ë½Ã¿¡´Â ¾Æ·¡¿Í °°ÀÌ a ű×ÀÇ onmouseover¿Í onfocus¿¡¸¸(Áß¿ä!) ÇÔ¼ö¸¦ ³Ö¾îÁÖ½Ã¸é µË´Ï´Ù.
 * <a href="someLink.blabla" onmouseover="rollOverImage(event, 'blablaTab', 'blabla_tab_on.gif');" onmouseover="rollOverImage(event, 'blablaTab', 'blabla_tab_on.gif');" />
 * @param event ±×³É event¶ó°í¸¸ ½áÁÖ¸é µË´Ï´Ù.
 * @param id ·Ñ¿À¹ö¸¦ Àû¿ëÇÒ À̹ÌÁö ¾Ù¸®¸ÕÆ®ÀÇ id °ª
 * @param src ¸¶¿ì½º°¡ ¿À¹öµÇ¾úÀ» ¶§ Ç¥½ÃµÇ´Â À̹ÌÁöÀÇ °æ·Î(»ó´ë ¶Ç´Â Àý´ë)
 * @param flag ¸¶¿ì½ºÀÇ ¿À¹ö »óŸ¦ ³ªÅ¸³»´Â º¯¼ö·Î½á, »ç¿ëÀÚ´Â ½Å°æ ¾µ ÇÊ¿ä°¡ ¾ø½À´Ï´Ù.
 */
function edu_RollOverImage(event, id, src, flag){
	event = event?event:window.event;
	var aObj = event.target?event.target:event.srcElement;
	var imgObj = document.getElementById(id);
	if(flag==undefined) flag = true;
	if(flag){
		if(!imgObj._src) imgObj._src = imgObj.src;
		imgObj.src = src;
	}else{
		if(imgObj._src) imgObj.src = imgObj._src;
	}

	if(!aObj.onmouseout){
		aObj.onmouseout = function(event){
			edu_RollOverImage(event, id, null, false);
		};
	}
	
	if(!aObj.onblur){
		aObj.onblur = function(event){
			edu_RollOverImage(event, id, null, false);
		};
	}
}