fulloverlay

Fulloverlay refers to a full-screen overlay layer rendered atop application content. In practice, it covers the entire viewport and typically serves as a user interface element, such as a menu, modal dialog, tutorial, or notification, that temporarily supersedes the underlying content.

Implementation may vary by platform. In web development, fulloverlay is commonly realized with CSS that fixes an element to all edges of the window and controls its visibility and opacity. In graphics engines, it is produced by rendering a full-screen quad with a shader, compositing operations, and a separate render target. The overlay can be opaque or translucent, animated, and may include interactive controls.

Applications include immersive menus in games, onboarding flows, streaming software overlays, privacy screens during screen capture, and application-wide notifications that require user attention.

Accessibility considerations are important: overlays should provide a clear focus trap, keyboard dismiss (Escape), and proper ARIA labeling so assistive technologies announce the overlay appropriately.

Fulloverlay is related to, but distinct from, fullscreen modals and picture-in-picture overlays. It is a general descriptive term rather than a formal standard, and its exact meaning can vary by developer or product.