function effect_tables (
  str_tableid, // table id (opt.)
  num_header_offset, // how many rows to skip before applying effects at the begining (opt.)
  num_footer_offset, // how many rows to skip at the bottom of the table (opt.)
  str_odd_color, // background color for odd rows (opt.)
  str_even_color, // background color for even rows (opt.)
  str_mover_color, // background color for rows with mouse over (opt.)
  str_onclick_color // background color for marked rows (opt.)
) {
  // set defaults for optional parameters
  str_tableid = (str_tableid ? str_tableid : 'adatok');
  var obj_tables = (document.all ? document.all[str_tableid] : document.getElementById(str_tableid));

  var col_config = [];
  col_config.header_offset = (num_header_offset ? num_header_offset : 0);
  col_config.footer_offset = (num_footer_offset ? num_footer_offset : 0);
  col_config.even_color = (str_even_color ? str_even_color : '#A7D7DA'); // minden 1. sor háttérszíne
  col_config.odd_color = (str_odd_color ? str_odd_color : '#E5ECF2'); // minden 2. sor háttérszíne
  col_config.mover_color = (str_mover_color ? str_mover_color : '#E9E330'); // annak a háttérszíne, amelyiken az egér áll (opt.)
  col_config.onclick_color = (str_onclick_color ? str_onclick_color : '#cccccc'); // background color for marked rows (opt.)

  // init multiple tables with same ID
  if(obj_tables.length)
    for (var i = 0; i < obj_tables.length; i++)
      tt_init_table(obj_tables[i], col_config);
  // init single table
  else
    tt_init_table(obj_tables, col_config);
}

function tt_init_table (obj_table, col_config) {
  var col_lconfig = [],
    col_trs = obj_table.rows;
  if(!col_trs) return;
  for (var i = col_config.header_offset; i < col_trs.length - col_config.footer_offset; i++) {
    col_trs[i].config = col_config;
    col_trs[i].lconfig = col_lconfig;
    col_trs[i].set_color = tt_set_color;
    col_trs[i].onmouseover = tt_mover;
    col_trs[i].onmouseout = tt_mout;
//    col_trs[i].onmousedown = tt_onclick;
    col_trs[i].order = (i - col_config.header_offset) % 2;
    col_trs[i].onmouseout();
  }
}

function tt_set_color(str_color) {
  this.style.backgroundColor = str_color;
}

// event handlers
function tt_mover () {
  if(this.lconfig.clicked != this)
    this.set_color(this.config.mover_color);
}

function tt_mout () {
  if(this.lconfig.clicked != this)
    this.set_color(this.order ? this.config.odd_color : this.config.even_color);
}

function tt_onclick () {
  if(this.lconfig.clicked == this) {
    this.lconfig.clicked = null;
    this.onmouseover();
  }
  else {
    var last_clicked = this.lconfig.clicked;
    this.lconfig.clicked = this;
    if(last_clicked) last_clicked.onmouseout();
    this.set_color(this.config.onclick_color);
  }
}