function searchIndex (value, container)
{
    for (i = 0; i < container.length; i++)
    {
        if (container.options[i].value == value)
        {
            return i;
        }
    }
}


function swapLanguage ()
{
    langFrom = document.getElementById("lang-from");
    langTo = document.getElementById("lang-to");
    
    indexFrom = langFrom.selectedIndex;
    indexTo = langTo.selectedIndex;
    
    fromValue = langFrom.options[indexFrom].value;
    toValue = langTo.options[indexTo].value;
    
    toIndex = searchIndex (fromValue, langTo);
    fromIndex = searchIndex (toValue, langFrom);
        
    langTo.selectedIndex = toIndex;
    langFrom.selectedIndex = fromIndex;
    
}