Added a widget persistence API. This allows you to persist your notebooks interactive widgets. Two levels of control are provided: 1. Higher level- WidgetManager.set_state_callbacks allows you to register callbacks for loading and saving widget state. The callbacks you register are automatically called when necessary. 2. Lower level- the WidgetManager Javascript class now has get_state and set_state methods that allow you to get and set the state of the widget runtime.

Example code for persisting your widget state to session data:

::

%%javascript require(['widgets/js/manager'], function(manager) {

manager.WidgetManager.set_state_callbacks(function() { // Load

return JSON.parse(sessionStorage.widgets_state || '{}');

}, function(state) { // Save

sessionStorage.widgets_state = JSON.stringify(state);

});

});