Skim is a Input Method based on Scim, but suited to KDE. It is used to write Japanese, Chinese and other weird languages with more characters than one can cram on a keyboard. Its dependency on app-i18n/scim-qtimm is not enforced. Without this, Skim is basically useless, as it will start, but character substitution will not be triggered. Solution: add app-i18n/scimm-qtimm to all of app-i18n/skim's ebuilds' RDEPEND.
Do you really need to add scim-qtimm to use skim? skim is KDE interface for scim, which provides XIM and GTK+ immodule, and scim-qtimm is not necessary to run skim. What programme did you try? (At least scim-qtimm affects only if you are using qt based applications and you emerged qt with "immqt" or "immqt-bc" USE flag.)
Nah, it was probably something that I cannot manage to recreate now - unless I reinstall kde from scratch or something. If I find out what was wrong (and if it is relevant for the Bugzilla) I'll reopen the bug.
