There are PDF documents which, when opened, show a "This documents contains embedded files." message. These embedded files are indeed PDF files (file name ends in ".pdf"), but the only thing I can do is save them. It should be possible to view them directly, without having to save and load them temporarily. For example files, see http://www.standardsicherung.schulministerium.nrw.de/abitur-gost/fach.php?fach=2 (scrolling to the bottom, has four "2011" documents).
IMHO, this shouldn't apply to PDF files only: all the embedded files in a PDF should be able to be open directly in Okular, with the software that relies on their MIME type (configured in KDE or whatever desktop manager). Currently, you have to save them first and to open them with another tools (command line or file manager). Thanks! Best regards.
Updated link: https://www.standardsicherung.schulministerium.nrw.de/abitur-gost/fach.php?fach=2 click on "Beispielaufgaben für den 2. Prüfungsteil" - [PDF, 4.2 MB] - 27.10.2015 the URL is currently https://www.standardsicherung.schulministerium.nrw.de/abitur-gost/getfile.php?file=3977 but this can change again.
A "View file" button really improves the experience of working with embedded files. I posted a patch to https://git.reviewboard.kde.org/r/127351/ that adds a view button for any embedded file (not just PDF).
Many thanks for your effort, Daniel! Unfortunately, I have no idea how to test your patch and currently not the time to investigate.
Git commit 155dc14b55f8f02c72038abb4b4c6db3daa28b81 by Albert Astals Cid, on behalf of Daniel Lichtenberger. Committed on 23/03/2016 at 00:58. Pushed by aacid into branch 'Applications/16.04'. Added ability to view embedded files The selected embedded file(s) are extracted to QDir::tempPath() and the default application associated with the file type is launched with KRun. Double-click on an embedded file also launches the view action. The temporary files are cleaned up automatically when the dialog is closed. REVIEW: 127351 M +53 -1 ui/embeddedfilesdialog.cpp M +6 -0 ui/embeddedfilesdialog.h M +8 -5 ui/guiutils.cpp M +2 -0 ui/guiutils.h http://commits.kde.org/okular/155dc14b55f8f02c72038abb4b4c6db3daa28b81
Thanks!