var hilite_colour = "#dcdcdc";
var default_colour_1 = "#F5F5F5";
var default_colour_2 = "#ffffff";

function doHilite(obj){
  var elem = obj.currentTarget;
  elem.style.backgroundColor = hilite_colour;
}

function undoHilite(obj){
  var elem = obj.currentTarget;
  //alert(elem.getAttribute("default_colour"));
  elem.style.backgroundColor = elem.getAttribute("default_colour");
}

function autoColour(){
  var allTrs = getElementsByClass("ruler");
  for(var i =0; i < allTrs.length; i++){
    allTrs[i].style.backgroundColor = (i % 2 != 0 ? default_colour_1 : default_colour_2);
    allTrs[i].setAttribute("default_colour", (i % 2 != 0 ? default_colour_1 : default_colour_2));
    //allTrs[i].style.backgroundColor = allTrs[i].getAttribute("default_colour");
  }
}

listen("load", window, function(){
  mlisten("mouseover", getElementsByClass("ruler"), doHilite);
  mlisten("mouseout", getElementsByClass("ruler"), undoHilite);
  
  autoColour();
});

// simply assign all TR's to be treated with class='ruler'