The new GIMP supports pdf, and, associates itself with PDF files, which is really annoying. I used to use evince as the default viewer. Here is the way I find to set it back.
There are two files we need to edit. One is “/usr/share/applications/mimeinfo.cache”, which controls file associations. The other is “/usr/share/applications/gimp.desktop”, which we can disassociate GIMP with pdf files forever.
1. edit “/usr/share/applications/mimeinfo.cache”, search “application/pdf”, delete “gimp.desktop”
2. edit “/usr/share/applications/gimp.desktop”, search “MimeType”, delete “application/pdf”
btw, i am using Archlinux with Gnome