//function change lang. of url: from from_lang to to_lang
// chi, gb, eng
function ChangeLang(to_lang)
{
		tempurl = window.location.href;
		if (to_lang == "gb") {
			if (window.location.href.indexOf("eng") > 0) {
				tempurl = tempurl.replace("/eng/", "/chi/");
				tempurl = tempurl.replace("http://", "http://translate.itsc.cuhk.edu.hk/gb/") ;	
			}		
		}
		if (to_lang == "chi") {
			if (window.location.href.indexOf("gb") > 0) {
				tempurl = tempurl.replace("http://translate.itsc.cuhk.edu.hk/gb", "http:/") ;
			} else if (window.location.href.indexOf("chi") > 0) {
				tempurl = tempurl.replace("http://", "http://translate.itsc.cuhk.edu.hk/gb/") ;	
			} else 	if (window.location.href.indexOf("eng") > 0) {
				tempurl = tempurl.replace("/eng/", "/chi/") ;
			}
		}
		if (to_lang == "eng") {
			if (window.location.href.indexOf("gb") > 0) {
				tempurl = tempurl.replace("http://translate.itsc.cuhk.edu.hk/gb", "http:/") ;
			} 
			tempurl = tempurl.replace("/chi/", "/eng/");

		}
		window.location.href = tempurl;
}

// chi -> eng, ChangeLang('eng')
// chi -> gb , ChangeLang('chi')

// gb -> eng , ChangeLang('eng')
// gb -> chi , ChangeLang('chi')

// separate buttons
// eng -> chi , ChangeLang('chi')
// eng -> gb  , ChangeLang('gb')