support for Gimp/XCF tumbnails
It's not like The Gimp is a program few people know about... AFAIK it's actually one of those that greatly helped make GNU/Linux popular.
Gimp is able to generate miniatures of its native file format (XCF).
Why isn't tumbler able to do that? It seems absurd.
In order to make things easier for everyone, I also created a "duplicate" of this feature request on the GNOME gitlab.