Hi, there's a newer version (2.20) of glbsp than actual Portage version (2.10). I've attach a revisited ebuild (tested and working fine on AMD64) for this version.
Created attachment 96305 [details] ebuild for games-fps/glbsp-2.20
Created attachment 97527 [details] glbsp-2.20.ebuild Updated ebuild Addes "fltk" USE flag: it enables build of fltk-based graphic interface
Fixed, thanks.