gistfile1.js

App.NavPanelView = Ember.View.extend( JQ.Animate, {
  cssProperties: ['height'],

  closedHeight: 40,
  openedHeight: 500,

  mouseover: function(){
    var openedHeight = this.get('openedHeight');
    this.set('height', openedHeight);
  },

  mouseout: function(){
    var closedHeight = this.get('closedHeight');
    this.set('height', closedHeight);
  }
});