[Michi]

You can do it quite simply for Forumdisplay like this:

Find in forumdisplay.php:

  while ($thread=$DB_site->fetch_array($threads)) { // and $counter++<$perpage) {

Right after that, add:

  	  if($oror++ % 2 == 0)
	  {
	  	$tread[color] = "{secondaltcolor}";
	  }
	  else
	  {
	  	$tread[color] = "{firstaltcolor}";
	  }

And thats that. Then just add bgcolor="$tread[color]" to table cells in the template you want. You can also rename the variables "$oror" and $tread[color] to whatever you want.

And, if you're clever, you can also add the same thingy to what ever loop that lists threads, topics, posts etc.