bug #57193 aims to remove all gpgme except for gpgme-0.3.14-r1 and 0.9.0-r1 So make this happen all progams that depend on gpgme-0.3.14-r1 like sylpheed need to be patches as the installation locations change. Please add a version sylpheed-0.9.12-r3.ebuild by patching against sylpheed-0.9.12-r2.ebuild. I will, once all the dependancies are worked, out put out a grand gpgme stabilising bug to all the arches stablising gpgme and all the ebuilds like this one that have needed to be changed. After that - remove all old things that depend on gpgme that aren't conformant to the above two ebuilds. After that clean out gpgme. Hopefully then gpgme depancies can go back to depending on a specific revision of an ebuild. I hope there is no object to me removing gpgme-0.3.16. Sometime not to distantly sylpheed will move to the modem gpgme-0.9+ dependancy stage.
Created attachment 37519 [details, diff] patch against sypheed-0.9.12-r2.ebuild
Also existing versions of sylpheed that use gpgme will need to explicitly depend on gpgme versions0.3.16 or 0.3.14. This is so 0.3.14-r1 doesn't get used for <=sylpheed-0.9.12-r2 cause it will break - library and headers have moved. I noted that mail-client/sylpheed-0.9.12-r{1,2} are still masked (for gtk2 reasons?)
Your patch solved the compile time troubles I had (bug #60684). I took the opportunity to uninstall all the slotted gpgme instances I had because one of them made sylpheed-gtk2 disable GPG, re-installed only 0.9.0-r1 and 0.3.14-r1, et voila, it's hopping along nicely again.
commited sypheed-0.9.12-r3 which hopefully fixes it. Currenlty masked awaiting testing by the real maintainers.
Oh... I was late 1 day. I committed -r3 and -r4 to fix this bug.