My goto font for code text editing, in my own editor, has, for years, been Consolas.
I thought its coverage was good but then I discovered that W10 was adding an automatic fallback so even my Ancient Egyptian hieroglyphics font (U+13000 et al) would appear.
Now my editor (internally UTF-8 multi-byte but switching to WCHAR for display including packing two part 21 bit Unicode which the SDK handles nicely) has offered a pop-up box that provided a quick and easy access to characters not on my keyboard and that used GetFontUnicodeRanges() to determine the coverage.
This is obviously now woefully inadequate. I've searched but not found a way to determine what character codes will result in a character on the display and yet Windows is doing it effortlessly at runtime. I can ask about any individual font I want to load but not what will happen.
I must be missing something. I really don't want to resort to writing whole blocks of text to an HDC to a bitmap and then pattern matching on that for the old rectangle or the ? in a box we all know so well.
Has somebody already done this? Is there a magic trick I am missing? I am retired now so I have time to delve but I've run out of ideas.