PowerAda Edit: Can't Edit Original Source
Clicking the Edit File button in a browser will first try to edit the source pointed at by the library (the filename that is shown in the browser).
This dialog means that this file does not exist. However, powerada can extract a copy of the source from the library, giving you an exact copy of the source you are browsing.
Clicking OK will bring up a file selection dialog, in which you choose the name you would like to save the new file under.