The way Paint.Net 3.5 handles fonts, turns out to be a real disaster - because fonts that are a subset of a given font family are just not seen, not listed, and thus cannot be used.
For example: om my Win7 system the Arial font family contains 10 installed fonts in three subsets: (1, main subset) Regular, Bold, Italic, Italic Bold; (2, narrow subset) Narrow, Narrow Bold, Narrow Italic, Narrow Italic Bold; (3, extrabold subset) Black, Black Oblique.
In this example, Paint.Net will see and list only the four fonts in 1, the main set. The six alternative Arial varieties in subsets 2 and 3 will not be seen or listed, and therefore those six Arial fonts cannot be used in image editing.
In my opinion this is a major bug, a real show-stopper, and I must say that I would expect something like this in a beta version, but I'm really surprised this was not corrected for the final 3.5 versions! I can only hope this will be corrected soon.