Edit

Sometimes users use links to websites within an image gallery. These usually are identified by mime type "text/html", "application/xhtml+xml", or similar. If this mime type is detected these links should not be treated as image.

The example here shows a way to handle these external media items: http://universalviewer.io/examples/?manifest=http://wellcomelibrary.org/iiif/b17502792/manifest#?c=&m=&s=&cv=&manifest=https%3A%2F%2Fedsilv.github.io%2Ftest-manifests%2Fdefaultextension.json --> see #9712

Handling of webapp URIs already works in the simple image gallery, see #8028 for details on open issues with this viewer.