I installed the newest Firefox version on my Debian 9.8 machine. Now I would like to use evince as my default PDF viewer but whenever I try to select it in the "use other" dialog of the corresponding Firefox settings, it just doesn't exist in the list of programs. The viewer is definitely working if I open it by calling "/usr/bin/evince".
I installed Firefox via snap but evince was installed via apt-get. Could that be the issue?