I remember Derek Bourgeois was asking about having accidentals available as part of trill lines last July. It was said to be in the works and that it would hopefully make the first release. However, I don’t think I saw it as part of the list of available features. Will it be included in Wednesday’s release? And if not, will there be a workaround?
Dorico does allow you to show accidentals above/below trills, but it’s an incomplete implementation: the plan is that the accidentals you on the ornament will affect the prevailing accidental calculation, i.e. that you can introduce or cancel an accidental on an ornament, and the notes later in the bar will take notice of that accidental. We haven’t had a chance to finish that off yet, so although you can show an accidental on the trill, it’s purely cosmetic at the moment.