sylpheed-claws-2.6.0 will link to libgpm if gpm is installed, but does not list gpm as a dependency. If gpm is not installed it will build quite happily and will not link to libgpm. This causes problems with depclean.
Need more info as it doesn't happen here, so must be conditional on something and I don't see any mention of gpm in configure/makefile.
I believe some other dependency is bringing the libgpm link, and I can't see a way in SC ebuild to fix this. I mean, we could add a gpm USE flag bringing in gpm dependency, but that wouldn't really solve anything, especially in case of USE="-gpm" ...