To add to low the other comments. I would add two points: 1. It depends on the language you deal with. 2. It depends on the input framework you are using.
A number of the languages I deal with use combinations of base characters and diacrtics where some combinations have precomposed forms and others don't. When developing keyboard layouts for such languages using simple input frameworks you have to use combining diacritics or a wierd mix of combining and composed. With more sophisticated input frameworks you have more flexibility and control. Andrew
