	function show_calendar4(str_target, str_datetime) {
		var arr_months = ["January", "February", "March", "April", "May", "June",
			"July", "August", "September", "October", "November", "December"];
		var week_days = ["Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"];
		var n_weekstart = 1; // day week starts from (normally 0 or 1)
		
		var dt_datetime = (str_datetime == null || str_datetime =="" ?  new Date() : str2dt4(str_datetime));
		var dt_prev_month = new Date(dt_datetime);
		dt_prev_month.setMonth(dt_datetime.getMonth()-1);
		if (dt_datetime.getMonth()%12 != (dt_prev_month.getMonth()+1)%12) {
			dt_prev_month.setMonth(dt_datetime.getMonth());
			dt_prev_month.setDate(0);
		}
		var dt_next_month = new Date(dt_datetime);
		dt_next_month.setMonth(dt_datetime.getMonth()+1);
		if ((dt_datetime.getMonth() + 1)%12 != dt_next_month.getMonth()%12)
			dt_next_month.setDate(0);
		
		var dt_firstday = new Date(dt_datetime);
		dt_firstday.setDate(1);
		dt_firstday.setDate(1-(7+dt_firstday.getDay()-n_weekstart)%7);
		var dt_lastday = new Date(dt_next_month);
		dt_lastday.setDate(0);
		
		// html generation (feel free to tune it for your particular application)
		// print calendar header
		var str_buffer = new String (
			"<html>\n"+
			"<head>\n"+
			"	<title>Calendar</title>\n"+
			"</head>\n"+
			"<body bgcolor=\"White\">\n"+
			"<table class=\"clsOTable\" cellspacing=\"0\" cellpadding=\"0\" border=\"0\" width=\"100%\">\n"+
			"<tr><td bgcolor=\"#3D3D3D\">\n"+
			"<table cellspacing=\"1\" cellpadding=\"3\" border=\"0\" width=\"100%\">\n"+
			"<tr>\n	<td bgcolor=\"#F0F7FF\"><a href=\"javascript:window.opener.show_calendar4('"+
			str_target+"', '"+ dt2dtstr4(dt_prev_month)+"');\">"+
			"<img src=\"images/button_l.gif\" width=\"16\" height=\"16\" border=\"0\""+
			" alt=\"previous month\"></a></td>\n"+
			"	<td bgcolor=\"#F0F7FF\" colspan=\"5\">"+
			"<font color=\"black\" face=\"tahoma, verdana\" size=\"2\">"
			+arr_months[dt_datetime.getMonth()]+" "+dt_datetime.getFullYear()+"</font></td>\n"+
			"	<td bgcolor=\"#F0F7FF\" align=\"right\"><a href=\"javascript:window.opener.show_calendar4('"
			+str_target+"', '"+dt2dtstr4(dt_next_month)+"');\">"+
			"<img src=\"images/button_r.gif\" width=\"16\" height=\"16\" border=\"0\""+
			" alt=\"next month\"></a></td>\n</tr>\n"
		);
	
		var dt_current_day = new Date(dt_firstday);
		// print weekdays titles
		str_buffer += "<tr>\n";
		for (var n=0; n<7; n++)
			str_buffer += "	<td bgcolor=\"#F0F7FF\">"+
			"<font color=\"black\" face=\"tahoma, verdana\" size=\"2\">"+
			week_days[(n_weekstart+n)%7]+"</font></td>\n";
		// print calendar table
		str_buffer += "</tr>\n";
		while (dt_current_day.getMonth() == dt_datetime.getMonth() ||
			dt_current_day.getMonth() == dt_firstday.getMonth()) {
			// print row header
			str_buffer += "<tr>\n";
			for (var n_current_wday=0; n_current_wday<7; n_current_wday++) {
					if (dt_current_day.getDate() == dt_datetime.getDate() &&
						dt_current_day.getMonth() == dt_datetime.getMonth() &&
						dt_current_day.getYear() == dt_datetime.getYear())
						// print current date
						str_buffer += "	<td bgcolor=\"#FF0000\" align=\"right\">";
					else if (dt_current_day.getDay() == 0 || dt_current_day.getDay() == 6)
						// weekend days
						str_buffer += "	<td bgcolor=\"#F0F0F0\" align=\"right\">";
					else
						// print working days of current month
						str_buffer += "	<td bgcolor=\"white\" align=\"right\">";
					if (dt_current_day.getMonth() == dt_datetime.getMonth())
						// print days of current month
						str_buffer += "<a onClick=\"javascript: window.opener.document.getElementById('"+str_target+
						"day').value='"+dt2day(dt_current_day)+"';window.opener.document.getElementById('"+str_target+
						"month').value='"+dt2month(dt_current_day)+"';window.opener.document.getElementById('"+str_target+
						"year').value='"+dt2year(dt_current_day)+"';"+
						"window.close();\" href=\"#\">"+
						"<font color=\"black\" face=\"tahoma, verdana\" size=\"2\">";
					else 
						// print days of other months
						str_buffer += "<a onClick=\"javascript:window.opener.document.getElementById('"+str_target+
						"').value='"+dt2dtstr4(dt_current_day)+"'; window.close();\" href=\"#\">"+
						"<font color=\"gray\" face=\"tahoma, verdana\" size=\"2\">";
					str_buffer += dt_current_day.getDate()+"</font></a></td>\n";
					dt_current_day.setDate(dt_current_day.getDate()+1);
			}
			// print row footer
			str_buffer += "</tr>\n";
		}
		// print calendar footer
		str_buffer +=
			"</table>\n" +
			"</tr>\n</td>\n</table>\n" +
			"</body>\n" +
			"</html>\n";
	
		var vWinCal = window.open("", "Kalender", 
			"width=225,height=200,status=no,resizable=yes,top=200,left=200");
		vWinCal.opener = self;
		vWinCal.focus();
		var calc_doc = vWinCal.document;
		calc_doc.write (str_buffer);
		calc_doc.close();
	}
	// datetime parsing and formatting routimes. modify them if you wish other datetime format
	function str2dt4 (str_datetime) {
		var re_date = /^(\d+)\/(\d+)\/(\d+)$/;
		if (!re_date.exec(str_datetime))
			return alert("Invalid Datetime format: "+ str_datetime);
		return (new Date (RegExp.$3, RegExp.$1-1, RegExp.$2));
	}
	function dt2dtstr4 (dt_datetime) {
		return (new String (
				(dt_datetime.getMonth()+1)+"/"+dt_datetime.getDate()+"/"+dt_datetime.getFullYear()));
	}
	function dt2month (dt_datetime) {
		return (new String (
				(dt_datetime.getMonth()+1)));
	}
	function dt2day (dt_datetime) {
		return (new String (
				(dt_datetime.getDate())));
	}
	function dt2year (dt_datetime) {
		return (new String (
				(dt_datetime.getFullYear())));
	}
	var datelike = new RegExp(/^(3[01]|0[1-9]|[12]\d)\-(0[1-9]|1[012])\-\d{4}/);
