function addFormEnhancers() {
  var searchField = $('search_terms');
  if (searchField != null) {
    searchField.onfocus = function() {
      if (this.value == this.defaultValue) this.value = "";
    }
    searchField.onblur = function() {
      if (this.value == "") this.value = this.defaultValue;
    }
  }
}
addLoadEvent(addFormEnhancers);