var cat_closed = 1;
var catids = new Array();
var counter = 0;

function changeCat() {
  var c;
  if (cat_closed == 1) {
    // open all the closed ones
    for (c in catids) {
      if (document.getElementById('cat' + catids[c])) {
        document.getElementById('cat' + catids[c]).style.display = "block";
      } else {
        return;
      } 
      if (c== catids.length - 1) {
        break;
      }
    }   
    cat_closed = 0;
  } else {
    // close all the open ones
    for (c in catids) {
      document.getElementById('cat' + catids[c]).style.display = "none";
      if (c== catids.length - 1) {
        break;
      }
    }   
    cat_closed = 1;
  }
  return false;
}