There are instances, though, where a document can be "opened" with an application that is not listed on that "Open With" choice. I have a PDF file on my desktop (document for our Samsung 65" Smart TV). As expected, when I double click on that file, it launches Adobe Acrobat Pro V10 (which I have). But, I can also use the Writer Document module for LIbreOffice to open it. What I do is launch LibreOffice, select the Writer Document module, select Open from the File module, and then select that PDF document. That module is not listed in the "Open With" list following Indago's instructions.