Comment 36 for bug 1551949

I got a question on chat about using SkiaPDF instead of cairo for this and I might as well add what info I have here.

SkiaPDF does indeed [have functionality to annotate](https://github.com/google/skia/blob/c0bd9f9fe533a7b8644392240c1250195aaee537/include/core/SkAnnotation.h) the PDFs in generates. However, although we use Skia, we [only made an experimental start on integrating and using SkiaPDF](https://mzl.la/3iZiU7v) as a printing backend. Finishing that off is probably still a fair amount of work. For anyone looking into fixing this bug the expedient way forward is most likely to try porting the functionality from a newer version of cairo to our old, in-tree version, as suggested by Jeff in comment 20.