Created attachment 8647999 [details] screenshot of the "Opening..." dialog box User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:40.0) Gecko/20100101 Firefox/40.0 Build ID: 20150812163655 Steps to reproduce: 1. Start Firefox 40.0.2 with a new profile. 2. Toggle pdfjs.disabled to true (e.g. for security reasons). 3. In Preferences → Applications, for "Portable Document Format", set "Always Ask". 4. Click on a link offering a PDF file, e.g. on https://www.vinc17.net/research/index.en.html#slides (there's the choice between "PDF" and "gzipped PS", so that one can see that what works with "gzipped PS" doesn't work with "PDF"). Actual results: A dialog box appears, and after "Open with", I get a bar with no text in it (see screenshot). Expected results: There's should be some text.
I forgot to say that this follows bug 1194663. Changes done there may affect this bug.