Wraps FPDFAnnot_SetFontColor. Routes through a transient form-
fill environment per PDFium's API.
See also
pdf_annot_font_color() for the reader counterpart.
Wraps FPDFAnnot_SetFontColor. Routes through a transient form-
fill environment per PDFium's API.
pdf_annot_font_color() for the reader counterpart.