OO does a poor job of rendering unicode combined characters. I figured it was a
Linux problem, until I noticed that the little Ubuntu accessory, Tomboy Notes,
renders combined characters perfectly.

Tone mark over upper case character: Tomboy puts the tone mark above the
character; in OO the tone mark steps on the character.

Combined nasalization and tone mark: Tomboy puts the tone mark above the
nasalization tilde; OO renders them on top of each other.

Combined nasalization and tone mark over upper case character: Tomboy, perfect;
OO, let's not even go there.

Example: O + U0303 should display each character of the combined character, so
that it looks like U00d6. Add a high tone mark such as U0301, and the tone mark
should appear above the tilde. As it is they are all mashed together and the
diacritics are not distinguishable. Printing gives the same results.

It's mostly readable in OO, but some tone marks cannot be distinguished, and it
is not of a quality to be printed and distributed. If my friends in Liberia want
a Bassa document written in OO, they have to save it as an MS file on media,
find a Windows computer, open the file in Word (or Excel) and then print it. 

Not ideal. (But at least it's a work-around they can probably manage for now.)