function characters_counter(dest, src, lenght)
{
    if (!lenght) lenght = 255;

    chars_string    = document.getElementById(src).value;
    chars_present   = chars_string.length;
    chars_left      = lenght - chars_present;
    
    document.getElementById(dest).innerHTML = chars_left;
}

function value_exists(arr_src)
{
    first_el_number = null;
    wrong_values    = 0;
    arr_src         = arr_src.split (", ");
    
    for ( i = 0; i < arr_src.length; i++ )
    {
        obj = document.getElementById(arr_src[i]);
        if ( obj )
        {
            chars_string = "";
//            chars_string = obj.getAttribute("value");
            chars_string = obj.value;
            if ( chars_string == "" ) 
            {
                if ( first_el_number == null ) 
                    first_el_number = i;
                    
                wrong_values++;
            }
        }
    }
    if ( wrong_values != 0 )
    {   
        if ( wrong_values == 1 )
            msg = "Недопустимое значение для обязательного поля";
        else
            msg = "Недопустимые значения для обязательных полей";
        
        alert ( msg );

        document.getElementById(arr_src[first_el_number]).setActive();
        return false;
    } else {
      return true;
    }
}

function item_display_trigger(src)
{
    state = document.getElementById(src).style.display;
    
    if ( state == "none" ) state = "block";
    else state = "none";
    
    document.getElementById(src).style.display = state;
}

function show_big_image(bigimg, x, y)
{
    window.open(
        "images/" + bigimg, 
        null, 
        "width=" + x + ",height=" + y + ",status=yes,toolbar=no,menubar=no,location=no"
    );
}