I have been working with Sitecore Marketplace since it was released, built a couple of custom fields, some for work and some for run, if you have not seen my previous blog post, here is the link for it, in which I show how to create a custom field for image selector from lytho DAM, and how you can add it to your datasource template; while doing that we ran into a case where we see a limitation and working with Sitecore team to register a feature request; if you're intrested keep reading.
