In order to generate the appearance for multiline text a basic plain text block composer needs to be developed.
- box model
- paragraph separation
- line breaking
- horizontal and vertical alignment
- font setting, line height …
Conceptually it should also include writing mode likely with the only initial implementation being lr-tb.
There should be no new dependencies on projects such as ICU which will limit the capabilities but should be acceptable to the needs of form filling.
To not create the false assumption that this is a generic composer it will be sub packaged within the (AcroForms) forms package(s).