If you start Kuroo (app-portage/kuroo-0.80.2) the first time, "Do not add the packages to the world profile (--oneshot)" is enabled by default. Why? If you type emerge on the commandline there isn't it also enabled default.
You should probably send this upstream.
Oh, sorry. I thought each package into the category app-portage is maintained by gentoo itself.
See http://kuroo.org/kuroo/ticket/231