Hi Matt,
After investigating this issue, the development team has informed me that it would not be possible to implement this functionality since the form''s fields appearance is stored in the PDF file as graphics primitives and we currently do not parse the graphics primitives when we read an existing PDF file. Currently the only possible solution is to get the bounds of the field and draw on top of it. Here is a sample
FillForm_2003_6c712252.zip
Issues with the sample
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1) Currently it is not possible to get the page associated with a form field but this functionality can be added easily.
2) This approach does not permit modifying the font or color of text.
Sorry for the confusion. Please let me know if you have any questions.
Best regards,
Stephen.