Just a quick update on the multi image Customizer control experiment.
When a user has selected some images using the WordPress Media Uploader I need to trigger an event telling the control that the new urls list is available.
To do that the
wp.customize.Events object is available as an extension of the Backbone Events object and packing the same power.
Binding a function to it and triggering it (here and here) has deprecated creating an extension to the Events object of my own.
Make it work, make it better.