OOo accepts either precomposed characters or letter-diacritic sequences from
different XKB keyboard layouts using either compose or dead-key, and from
various IMEs, but evidently does not convert to a common form, because searches
for one form cannot find the other. Example:

In Vietnamese, (Tiếng Việt), written in precomposed characters cut from some
source and pasted into OOo, a search for 'e' will not find 'ệ'. Given the sequence
e ̂  ̣  , which renders as ̣ệ, a search for 'e' will find it there.

The same issue exists in European languages with characters such as á, ñ, å.