Just found this cool tip on Twitter (yes, there is useful stuff there). Click on a filename, then press Command-Option-C to copy the PATH of the file into the clipboard. You can also right click while holding the option key and choose Copy as Path from the popup menu. Either way, you can then paste the path into Panorama, for example for use with the openfile statement or fileload( function. (Click the play button to watch the movie below.)
Of course another option is to simply drag the file (or folder) onto the procedure editor window.