Snippet of resizeParent function needed to resize your plugin in TheCity

ResizeParentSnippet

var resizeParent = function (url) {
    var target = target || parent;
    var body = document.body;
    var html = document.documentElement;
    var height = Math.max(body.scrollHeight, body.offsetHeight, html.clientHeight, html.scrollHeight);
    target.postMessage(height, url);
}

// usage
var parentUrl = "https://YOURSUBDOMAIN.onthecity.org";
resizeParent(parentUrl);

Here is a full example: https://gist.github.com/jameymcelveen/6793546

Are you on the other Github repo? I took your original and tweaked it, submitted a pull request. Basically, it just sets a setInterval in case the document height changes.