My understanding of USE flags was that they enabled optional functionality in packages, and that if a program required something to work it would be installed automatically. However, if you don't have emul-linux-x86 in your USE flags, emul-linux-x86-baselibs won't be pulled in as a dependency, which means that sunbird won't start. Since the only way sunbird-bin will work on amd64 is if you have emul-linux-x86-{baselibs,gtklibs} installed, I don't think it makes sense for them to be optional dependencies... Reproducible: Always Steps to Reproduce: 1. 2. 3.
This has been fixed since January: 14 Jan 2005; Jan Brinkmann <luckyduck@gentoo.org> mozilla-sunbird-bin-0.2.20040812.ebuild, mozilla-sunbird-bin-0.2.20041112.ebuild: back to amd64 from of emul-linux-x86