The way to do this would be to make the "file" correspond to the QDL page. So in addition to being able to "add a new sub-page", you would also be able to upload a file. If it was a text file, the contents of the file would go into the page, and you'd be able to edit it in QDL. If it was a binary file, the disclosure widget would be replaced with an icon appropriate for that binary file format. Clicking the icon would download the file, because that would be the closest equivalent to opening the page in QDL. You would still be able to "edit" a binary file, so that you could get to the rights settings, but there wouldn't be anything in the editor window, since it would merely be a data source.

The corresponding action menu behaviors would be straight-forward. Deleting the item would mark the page as deleted, and mulching it would delete the file from the server, and remove the QDL page from the system. Cutting and copying links would work the same as for any other page. Pasting a link into the page would be disabled.