Immediate mode, retained state
Build the interface every frame with plain procedures; boxes keep their state by key: animations, scroll, focus, text fields. Size kinds, signals and tag-based themes, after the RAD Debugger's UI layers.
Features
Its own renderer
Rounded rects, shadows, gradients, blurs and backdrops, masks, layers, transforms, Slug text from outlines (hinted when small), video; Direct3D 11 on Windows, WebGPU on Linux, damage tracking and a frame pacing model that never stretches a resize.
Text done properly
DirectWrite on Windows, or the native backend everywhere (Fontations, HarfRust, ICU4X): shaping, bidi, grapheme clusters, line breaking, colour emoji (COLR v1, and CBDT on Linux), fallback fonts.
Widgets
Fields and editors (wrapped, highlighted, secret), menus, pickers with fuzzy matching, virtualized tables and trees, splitters, tabs, dialogs, toasts, popovers, charts, drag and drop, find in page.
The platform
Integrated title bars with snap layouts, DPI, IME, clipboard, file dialogs, tray icons, single instance, accessibility through AccessKit; X11 and Wayland on Linux.
Tested
Windowless tests with pixel comparisons on WARP, every package through the WebGPU backend, a Linux job; pinned dependencies (Odin, crates, wgpu-native) by SHA-256. A whole program is driven end to end over the Chrome DevTools Protocol, which Puppeteer, Playwright and your own scripts can use too: clicks, keys, screenshots, the accessibility tree, without touching the mouse. A run can be kept as a timeline, a page with a picture per action and every frame's time, then played back and compared. Chrome's own DevTools attach to a window: its boxes in Elements, their styles and colours edited live, what a screen reader gets for each.