Add a drag and drop container widget

To have a drag and drop zone in Studio, it is necessary to reimport the following widget as a template :
https://github.com/nuxeo/nuxeo-jsf/blob/master/nuxeo-platform-webapp-base/src/main/resources/web/nuxeo.war/widgets/drop_zone_widget_template.xhtml

and then put whatever needed inside, like a content-view.
It would be simpler to have this widget in the built-ins or options on the container widget to make them drop-zones (a dropContext property is then required).

According to : http://doc.nuxeo.com/x/BAJu
Defining the dropzone is not enough, an action must xml contributed, so a link to the doc page or some help is needed with the drop zone feature (either on a specific widget or the default container)