I've noticed artrage now supports dragging files into it's window (then gives an option to import/create tracing image/etc). This is great!
I've also noticed that you can't drag files in from iPhoto. This should work just like normal, however, iPhoto files are stored inside the "iPhoto library" document. Effectively these files are actually directories like any other, but disguised as single files to simplify the user dealing with them. In the mac vernacular they're called "packages" and can be browsed by right-clicking on the file and choosing "view package contents".
Applications which understand these collections can browse them like any normal directory. It seems that artrage is getting confused by the package and giving up. Browsing the package in finder and dragging the file directly from the embedded folder also fails.
It would be great if artrage understood packages, and I believe it should not be hard to implement. This would allow us to drag assets directly from iPhoto or other package aware applications (curio, i think evernote and circus ponies notebook, etc).
Thanks for the great work on AR3 by the way.