Xorg is configured to assume US keyboard layout, and I set "use system layout" option on ibus-setup enabled, but when I switch to Japanese Input Method on IBus, such as Mozc, JP keyboard layout is forced. This bug is also reported on the upstream <http://code.google.com/p/ibus/issues/detail?id=1558> and fixed on the trunk (related commits: <https://github.com/ibus/ibus/commit/4b2f6a477019b50375aba2e5f9c43e618b6905ad> and <https://github.com/ibus/ibus/commits/master>). The behavior is quite inconvenient, so I made ebuild with the upstream fix applied. Some parts of IBus is written in vala, and release of IBus source code includes generated C code from vala. The ebuild now uses included C code when vala USE flag is not specified and the upstream fix is for vala code, so if you avoid dependency on vala, the patch used by ebuild should include diff of automatically generated C code. It is a bit ugly, and if dependency on vala is permitted, the patch is simple. So I'll attach two patch to app-i18n/ibus, one is avoiding vala dependency and the other depend on vala.
Created attachment 341322 [details] the patch not depending on vala
Created attachment 341324 [details, diff] the patch depending on vala
Created attachment 341326 [details, diff] the patch not depending on vala (fixed) Sorry, I made a mistake.
I just added the patch into the tree. Thank you for your contribution.