gistfile1.js

// PhotoThumbView 
  showPhoto: function () {
    // remove the selected class from other elements
    $(this.el).siblings().removeClass('selected');
    // add it
    $(this.el).addClass('selected');
    // add the photo to the viewer
    a.viewer.addModel(this.model, $(a.mainpane.el).scrollTop());
    // add object to history
    a.navigate('photo/'+this.model.get('id'), false);
    // save our current state for the history
    a.viewer.saveState();
  },