Comment by AndriyKunitsyn

Well, you were talking about testing, development of DPI-aware apps is another thing. It requires the developers to be, well, DPI-aware, but I don't think there are particular obstacles to that in winapi itself.

>Have you ever tried to write HiDPI-aware Win32 code?

I haven't. I don't think there's any reason to, I'm more of a wxwidgets fan. I don't think even Microsoft makes applications in raw WinAPI.

>I suggest enabling HiDPI in Control Panel sometimes and marveling at how many Win32 apps just don’t notice and draw as postage stamps.

The default behaviour of a DPI-unaware app in Windows is to scale everything by the scale factor. Which - yes, looks completely awful and blurry, but that's not what you describe.