Grace-5.1.17 was released as a maintenance release of the 5.1 series, the authors recommend an update. I used the grace-5.1.14 ebuild (in portage) and just renamed it. Emerging it was successful and grace seems to work as expected (tested on x86, but I think it should be OK on other platforms.) Reproducible: Always Steps to Reproduce:
Created attachment 45599 [details] ebuild for grace-5.1.17 no changes from 5.1.14. Still uses grace-helpviewer-gentoo.diff from 5.1.13 (and 5.1.14).
Created attachment 55640 [details] ebuild for grace-5.1.18 grace-5.1.18 was released in the meatime. This is an ebuild for it. The only change in the ebuild was to correct the download location which has been changed. Compiles and grace works for me.
Fixed, thanks! Sorry for the delay.