This is all I found:

"It's written in C and has custom OpenGL renderer."

https://filepilot.handmade.network/

Made it himself

It looks like WPF but isn't. Sibling comment suggests sui generis, which explains the tiny size and lack of dependencies. This does make it blindingly fast but makes the keymappings different from what you'd normally expect. Haven't tested annoying cases e.g. two monitors with different DPI.

edit: report of poor CJK support https://news.ycombinator.com/item?id=43100494 ; Windows file system encoding is annoying because it's UTF-16.

This is always, always the tradeoff with custom UIs. The edge cases eat you alive.

I'm sorry, as I don't know.

I mean, I don't even know what you use to write "windows" applications anymore.

But are the stock frameworks that slow to justify rewriting the toolkit? I am under the impression that writing GUI toolkits was Hard.

Are there plans to make this cross platform?

It was written from scratch with a custom OpenGL renderer (a DirectX port is in progress for Windows) and a custom IMGUI layer on top.

You mean all those complex UI stuff code is written in immediate GUI? How maintainable/readable is the resulting code?

Way more maintainable than anything from MS that I'd have to deal with.

How about the CPU usage? Running a main loop at 60hz for a file manager sounds bit overkill.

Agree about the MS offerings. That's why I use cross-platform frameworks (wx, qt) even for the Win-only apps.

Give the demo a try. I compared the CPU usage to the win10 file explorer, and they look identical (both are minuscule); it's super impressive.

How is the support for CJK and insane Unicode like emoji surrogates? Dealing with some of those edge cases can break a man.