
function ShowCalendar( sFn, sValue )
{
	var aMonths = ["Enero", "Febrero", "Marzo", "Abril", "Mayo", "Junio",
		"Julio", "Agosto", "Septiembre", "Octubre", "Noviembre", "Diciembre"];

	var aWeekDays = ["Do", "Lu", "Ma", "Mi", "Ju", "Vi", "Sa"];
	var nWeekStart = 1; // 0:Domingo, 1:Lunes ...



	var dt_datetime = (sValue == null || sValue =="" ?  DsDt_GetCurZeroDate() : DsDt_Str2Date(sValue));
	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()-nWeekStart)%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>Calendario</title>\n"+
		"</head>\n"+
		"<body bgcolor=\"White\" onblur=\"self.focus()\">\n"+
		"<table class=\"clsOTable\" cellspacing=\"0\" border=\"0\" width=\"100%\">\n"+
		"<tr><td bgcolor=\"#4682B4\">\n"+
		"<table cellspacing=\"1\" cellpadding=\"3\" border=\"0\" width=\"100%\">\n"+
		"<tr>\n	<td bgcolor=\"#4682B4\"><a href=\"javascript:window.opener.ShowCalendar('"+
		sFn+"', '" + DsDt_Date2Str(dt_prev_month) + "');\">" +
		"<img src=\"/Images/Shared/Ico_Cal_Prev.gif\" width=\"16\" height=\"16\" border=\"0\""+
		" alt=\"Mes anterior\"></a></td>\n"+
		"	<td bgcolor=\"#4682B4\" colspan=\"5\">"+
		"<font color=\"white\" face=\"tahoma, verdana\" size=\"2\">"
		+aMonths[dt_datetime.getMonth()]+" "+dt_datetime.getFullYear()+"</font></td>\n"+
		"	<td bgcolor=\"#4682B4\" align=\"right\"><a href=\"javascript:window.opener.ShowCalendar('"+
		sFn+"', '" + DsDt_Date2Str(dt_next_month) + "');\">" +
		"<img src=\"/Images/Shared/Ico_Cal_Next.gif\" width=\"16\" height=\"16\" border=\"0\""+
		" alt=\"Mes Siguiente\"></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=\"#87CEFA\">"+
		"<font color=\"white\" face=\"tahoma, verdana\" size=\"2\">"+
		aWeekDays[(nWeekStart+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=\"#FFB6C1\" align=\"right\">";
				else if (dt_current_day.getDay() == 0 || dt_current_day.getDay() == 6)
					// weekend days
					str_buffer += "	<td bgcolor=\"#DBEAF5\" 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 href=\"javascript:window.opener."+sFn+
					"('" + DsDt_Date2Str(dt_current_day) + "'); window.close();\">"+
					"<font color=\"black\" face=\"tahoma, verdana\" size=\"2\">";
				else 
					// print days of other months
					str_buffer += "<a href=\"javascript:window.opener."+sFn+
					"('" + DsDt_Date2Str(dt_current_day) + "'); window.close();\">"+
					"<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 +=
		//"<form name=\"cal\">\n<tr><td colspan=\"7\" bgcolor=\"#87CEFA\">"+
		//"<font color=\"White\" face=\"tahoma, verdana\" size=\"2\">"+
		//"Time: <input type=\"text\" name=\"time\" value=\""+dt2tmstr(dt_datetime)+
		//"\" size=\"8\" maxlength=\"8\"></font></td></tr>\n</form>\n" +
		"</table>\n" +
		"</tr>\n</td>\n</table>\n" +
		"</body>\n" +
		"</html>\n";

	var vWinCal = window.open("", "Calendar", 
		"width=200,height=210,status=no,resizable=yes,top=200,left=200");
	vWinCal.opener = self;
	var calc_doc = vWinCal.document;
	calc_doc.write (str_buffer);
	calc_doc.close();
}

