[HiramNetherlands]

I suppose these are just alpha oddities. Control-dragging a file should, as Ken said, produce a link (in the form of a text string you can click, upon which the linked file will open in the associated application).

Having said that, I would prefer a simple drag action (i.e. without having to hold Control) to also produce a link. Who wants OmniFocus' database to fill up with files that are probably stored elsewhere on their machines already?

Apart from the size-of-database argument, I also think catch-all applications are not the way to go; PDFs and image files should open in Preview, not OmniFocus. (I don't now about Linkback, though. Do linkbacked files live in OF's database?)