Comment 10 for bug 1007423

Also likely the same issue: https://wiki.archlinux.org/index.php/IBus#LibreOffice

Quote:

If IBus does load but doesn't see LibreOffice as an input window, add this line to ~/.bashrc:
    export XMODIFIERS=@im=ibus
And then, you need to start ibus with "-xim -d", for example, add this line to ~/.xinitrc:
    ibus-daemon --xim -d
But the horrible thing is that you need to start LibreOffice in terminal.
If you're using KDE and the above doesn't work, install "libreoffice-gnome" and add this line to ~/.xprofile if you don't mind running LibreOffice in GTK2 mode:
    export OOO_FORCE_DESKTOP="gnome"
That'll make IBus work with LibreOffice, and you can start LibreOffice from anywhere -- not just the terminal.