UI model

Declarative code-first UI on a retained runtime, with built-in docking and workspaces and a dedicated GPU viewport.

What app code declares

App code describes structure: panels, trees, tables, property inspectors, toolbars, tab groups, splitters, and viewport placement. The framework owns layout, resizing, spacing, panel relationships, scrolling, focus, keyboard navigation, typography defaults, and docking behavior. App code configures exceptions only. No markup file, no stylesheet, no mandatory visual editor. UI description stays in version controlled code.

What the runtime owns

Layout, input, state, text, accessibility, docking, and workspace serialization. Declaring the UI must not rebuild it per frame. The runtime retains components, assigns stable identity to panels and rows, updates only what changed, and virtualizes large lists and tables.

Viewport separation

The central canvas gets a dedicated GPU path through the same Vulkan backend. The framework manages window, input, sizing, HiDPI, and frame pacing across UI and viewport as one system, so a heavy viewport frame never blocks panel input. UI controls and viewport content have separate performance budgets.

Rejected alternatives

• HTML, CSS, DOM: workable but too much separate machinery for dense native desktop tooling.
• Immediate-mode only: good for quick tools, weak for persistent state, text, keyboard workflow, and accessibility in full application shells.
• Verbose retained widgets without a declarative layer: sound runtime, but too much app code per panel.
• Visual editor as core model: acceptable as an optional addition, not the programming model.