"All opened files" or "all open files"?
"Opened files" does indeed mean "Files that have been opened" [and are assumed to be still open], but the adjective "open" does the job well, and sounds more natural to me.
"Opened files" does indeed mean "Files that have been opened" [and are assumed to be still open], but the adjective "open" does the job well, and sounds more natural to me.