var DefaultValue = function(def) {
  this.def = def;
  this.val = def;
  this.focused = false;
  var self = this;
  this.focus = function() {
    if (!self.focused && self.val == self.def) {
      self.val = "";
      self.focused = true;
    }
  };
  this.blur = function() {
    if (self.focused && self.val.length == 0) {
      self.val = self.def;
      self.focused = false;
    }
  };
};