function show_calendar(str_target, str_datetime) {
	var arr_months = ["Janvier", "Fevrier", "Mars", "Avril", "Mai", "Juin",
		"Juillet", "Aout", "Septembre", "Octobre", "Novembre", "Decembre"];
	var week_days = ["Di", "Lu", "Ma", "Me", "Je", "Ve", "Sa"];
	var n_weekstart = 1; // day week starts from (normally 0 or 1)

	var dt_datetime = (str_datetime == null || str_datetime =="" ?  new Date() : str2dt(str_datetime));
	var dt_prev_month = new Date(dt_datetime);
	dt_prev_month.setMonth(dt_datetime.getMonth()-1);
	var dt_next_month = new Date(dt_datetime);
	dt_next_month.setMonth(dt_datetime.getMonth()+1);
	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 width=100%  border=0 cellspacing=1 cellpadding=0><tr><td>\n"+
	  "<table width=100% height=15 border=0 cellspacing=0 cellpadding=0 bgcolor=3366CC>\n"+
        "<tr> \n"+
          "<td valign=top width=6><img src=../../images/corner1_cal.gif  width=6 height=6></td>\n"+
          "<td width=9><a id=calendar href=\"javascript:window.opener.show_calendar('"+
		 str_target+"', '"+ dt2dtstr(dt_prev_month)+"');\">"+
		"<img src=../../images/prev.gif width=9 height=9 alt=\"previous month\" border=0></a></td>\n"+
          "<td align=center width=100%><b><font color=\"white\" face=\"tahoma\" size=\"1\">"
		+arr_months[dt_datetime.getMonth()]+" "+dt_datetime.getFullYear()+"</font></b></td>\n"+
          "<td width=9><a id=calendar href=\"javascript:window.opener.show_calendar('"
		+str_target+"', '"+dt2dtstr(dt_next_month)+"');\">"+
		"<img src=../../images/next.gif width=9 height=9 alt=\"next month\" border=0></a></td>\n"+
          "<td width=6 valign=top><img src=../../images/corner2_cal.gif  width=6 height=6 border=0></td>\n"+
        "</tr>\n"+
      "</table></td></tr></table>\n"+

		"<table  cellspacing=\"1\" border=\"0\" width=\"100%\">\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 align=center bgcolor=\"#66CCFF\">"+
		"<font color=\"white\" face=\" tahoma\" size=\"1\">"+
		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 heder
		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())
					// print current date
					str_buffer += "	<td bgcolor=\"#FF9900\" align=\"right\">";
				else if (dt_current_day.getDay() == 0 || dt_current_day.getDay() == 6)
					// weekend days
					str_buffer += "	<td bgcolor=\"#E5E5E5\" 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 id=calendar href=\"javascript:window.opener."+str_target+
					".value='"+dt2dtstr(dt_current_day)+"'; window.close();\">"+
					"<font color=\"black\" face=\" tahoma\" size=\"1\">";
				else 
					// print days of other months
					str_buffer += "<a id=calendar href=\"javascript:window.opener."+str_target+
					".value='"+dt2dtstr(dt_current_day)+"'; window.close();\">"+
					"<font color=\"gray\" face=\" tahoma\" size=\"1\">";
				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" +
		"</body>\n" +
		"</html>\n";

	var vWinCal = window.open("", "Calendar", 
		"width=200,height=170,scrollbar=no,status=no,resizable=no,top=200,left=200");
	vWinCal.opener = self;
	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 str2dt (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.$2-1, RegExp.$1, RegExp.$4, RegExp.$5, RegExp.$6));
}
function dt2dtstr (dt_datetime) {
	return (new String (
			dt_datetime.getDate()+"-"+(dt_datetime.getMonth()+1)+"-"+dt_datetime.getFullYear()+" "));
}
function dt2tmstr (dt_datetime) {
	return (new String (
			dt_datetime.getHours()+":"+dt_datetime.getMinutes()+":"+dt_datetime.getSeconds()));
}

