Looks like 4.0 may have broken it

[lkwdwrd]

Just loaded up the thing in a new install to play with it and the preview has stopped working.

I assume it has something to do with extending one of the media views, but I haven't poked at the JS enough to know what's up. It looks to have a loading screen for media:

Just a friendly FYI :-)

[lkwdwrd]

Alright, had a chance to look through things. The register method changed quite a bit in 4.0.

Here it is in 3.9:

register: function( type, constructor ) {
    views[ type ] = constructor;
}

and here it is in 4.0:

register: function( type, constructor ) {
    var defaultConstructor = {
        type: type,
        View: {},
        toView: function( content ) {
            var match = wp.shortcode.next( this.type, content );

            if ( ! match ) {
                return;
            }

            return {
                index: match.index,
                content: match.content,
                options: {
                    shortcode: match.shortcode
                }
            };
        }
    };

    constructor = _.defaults( constructor, defaultConstructor );
    constructor.View = wp.mce.View.extend( constructor.View );

    views[ type ] = constructor;
}

The register method is being helpful and extending the wp.mce.Vew for us, that is already being done at line 239 of example-thing.js. The Backbone extend method expects an object, but we're passing it a constructor function. If you remove the extend call at line 239 and just pass the object as the view, it starts working fine.

View: {
    className: 'editor-thing',
    template:  media.template( 'editor-thing' ),
    initialize: function( options ) {
        this.shortcode = options.shortcode;
    },
    getHtml: function() {
        return this.template( _.defaults(
            this.shortcode.attrs.named,
            thing.defaults
        ) );
    }
},

This simple fix gets things going, but it looks like there was a lot of changes in the MCE views which renders some of the code in the example thing unnecessary. I'm still playing with it, may get to a pull request at some point.

Either way, thanks much for the example!