function listovaci_menu($db_tabulka_kategorie) {
    // Tato funkce zajistuje listovaci menu trid souboru, tj kategorie
    $prikaz = mysql_query("SELECT * FROM ".$db_tabulka_kategorie);
    // Zjistime pocet kategorii
    $formular = '<FORM NAME="kategorie" ACTION="index.php" METHOD="post" ENCTYPE="text/plain">';
    $formular = $formular.'<input type="hidden" name="kategorie" value="">';
    $formular = $formular.'<SELECT NAME="kategorie" onChange="submit();">';
    $dotaz = mysql_query("SELECT * FROM ".$db_tabulka_kategorie);
    while ($pole = mysql_fetch_array($dotaz, MYSQL_ASSOC)) {
        $formular = $formular."<OPTION VALUE=".$pole['nazev'].">".$pole['cely_nazev']."</OPTION>";
    }
    $formular = $formular."</SELECT>";
    $formular = $formular."</FORM>";
    return $formular;
}