Description of problem:
When opening files from a URL, Firefox will not try to open it in an external application.
Version-Release number of selected component (if applicable):
Consistently, on a RHEL 6.10 system with a GUI installed per https://access.redhat.com/solutions/5238.
Steps to Reproduce:
2. Set pdfjs.disabled = true in about:config.
3. Open a PDF in a URL (like https://www.gutenberg.org/files/11/11-pdf.pdf).
The file is immediately downloaded. When the folder icon in the download pop-up is clicked, instead of Nautilus appearing, the "Launch Application" window is shown.
The file open dialog box should pop up and ask whether to open the PDF in evince or download it. When the folder icon in the download pop-up is clicked, the Nautilus window for the download folder should be displayed.
Possibly related: https://bugs.centos.org/view.php?id=15113 'Firefox is unable to determine how to open Word documents'
There's is a fix for this by changing XDG_DATA_DIRS in /usr/bin/firefox to: