ibus-1.5.0 stable version has released about 2 years ago. https://code.google.com/p/ibus/ but, ibus-hangul, which is being in the portage, didn't updated to a new version and it looks like abandoned from an engineers' hand. please consider that should be managed. Thanks .
is there anyone to see this report? I will write ebuild for >=app-i18n/ibus-hangul-1.5
Fixed.