https://github.com/shatsky/lightning-image-viewer

Tiny desktop (pre)viewer which displays image in transparent overlay without any UI, allowing to look into specific image detail with single hand move (zoom with scroll and pan with drag simultaneously like in map apps, with nothing but display borders limiting visible image surface) and toggle between file manager and image view almost instantly (close with left click anywhere/keyboard Enter).

Also finished initial rewrite in Rust just hours ago:) (originally did it in C and intentionally tried to make it initially close to preceding C codebase before going further, so many things are still managed manually)