I am currently using Filezilla 3.7.3. on Linux Mint 17 and have trouble with the default .pdf-viewer. Ones I double-click on a .pdf-file in the embedded file browser, GIMP instead of okular/evince/adobe-reader opens. I browsed through the settings of Filezilla and asked Google, but I could not find a solution.
As I found an open thread in the Filezilla forum (https://forum.filezilla-project.org/viewtopic.php?t=16733) that didn't come to a solution, I decided to ask this question here and hope for help. Thanks!