Well I spent six hours going down a rabbit hole to figure out a work around. I thought maybe I could use their "web box" display item to load some Javascript to manipulate the page, but that lead to issues with crossdomain blocks, so in trying to figure out how to host an html file on the...
Yeah, I've been able to work around a great deal of the frustration, but after six years one would think that the feature-set for webapps would have grown more than it has.