rawproc, my hack raw processor uses wxWidgets wxImage/wxBimap classes to display renders, and they are quite obviously 8-bit. I think most of the GUI tools (wxWidgets, GTK?, Qt?) provide an 8-bit image rendering widget by default; if you want better, they expect use of the OpenGL/Direct3D interface.
More of an issue now with high-bitdepth/gamut displays, but my “customer base” hasn’t complained, yet.
Oh, I’ve used vkdt, seems easy enough to me. @hanatos even includes a thumbnail screen to select images for editing, something I’d scrap in a minute, but it’s his baby… rawproc’s ‘light table’ is the OS file manager - suck it up, customers!! 