/// <summary>
/// Launches the DatePicker page in a popup window,
/// passing a JavaScript reference to the field that we want to set.
/// </summary>
/// <param name="strField">String. The JavaScript reference to the field that we want to set,
/// in the format: FormName.FieldName
/// Please note that JavaScript is case-sensitive.</param>
function calendarPicker(strField)
{
            var leftpos = (screen.width-250) / 2;
            var toppos = (screen.height-190) / 2;
            var win = window.open('/common/DatePicker.aspx?field=' + strField, 'calendarPopup', 'width=250,height=260,resizable=no,left=' + leftpos + ',top=' + toppos);
            win.focus();
}