skim

skim is an input method platform based upon scim-lib under *NIX systems (including GNU/Linux and FreeBSD) systems optimized for KDE. It provides a GUI panel (named scim-panel-kde), a KConfig config module and SetupUIs for itself and scim-lib. It also has its own plugin systems which support on-demand loadable actions.

(skim has been incorporated in most distros, so you may want to check your distros repository first)

more details
http://www.scim-im.org/

1.4.5 Bug Fix release:
Fixed: crash issue when deleting helper properties
Improved: implement session management support to save user config when logout from session
Fixed: compilation with qt 3.3.6
Updated: Korean translation

1.4.4 Bug Fix release:
Fixed: -f option did not work properly
Fixed: name of Built-in compose (european keyboard support) IM
Fixed: kde 3.3 compatibility
Fixed: filter saving bugs
Improved: user can not disable the setupwindow plugin to prevent users from having no configure dialog by accident
Improved: display the name of the current IM by default
Added: Panjabi(pa) translation

1.4.3 Minor Bug fix release:
Improved: apperance consistency of buttons in main window
Fixed: compile problem with qt 3.3.5
Fixed: scim-setup could not be started

1.4.2 Minor Bug fix release:
Improved: added move up/down button in filter config dialog
Improved: added ComposeKeyFactory in IMEngine setup dialog
Fixed: a bug in configure script (affecting debian system)
Fixed: toggling main window mode did not update property buttons in it

1.4.1 Minor bug fix release:
Improved: embedded mode (in kicker) of main window
Fixed: build system issues in regarding to packaging and 64 systems

1.4.0 Stable release:
Fixed remaining build system issues