lookandfeel

Look and feel (L&F) describes the visual presentation and interactive behavior of a graphical user interface. It encompasses components such as buttons, menus, sliders, as well as typography, color schemes, iconography, and motion. L&F is distinct from application logic and data; it defines how the UI is rendered and how it responds to input, rather than what it does.

Many GUI frameworks implement a pluggable L&F or theming system. This allows developers to switch skins or target platform conventions without changing functional code. L&F can mimic native OS aesthetics or provide a custom theme to support branding and accessibility. The choice of L&F can influence perceived performance and usability, as well as consistency across an application.

Examples: In Java Swing, Look and Feel is a pluggable architecture with UI delegates, managed by a UIManager. Common options include Metal, Nimbus, Windows, and GTK, which can be selected at startup or changed at runtime. Other ecosystems use themes or styles: Qt offers styles like Fusion or Windows; GTK applies themes; Android uses themes and styles to control widget appearance and behavior; some web-based or cross-platform toolkits use CSS-like theming.

Considerations include balancing native appearance with branding, ensuring accessibility and readability across themes, and maintaining consistency of interaction patterns. Developers may test multiple L&F options to preserve keyboard navigation, contrast, and localization, since font sizes and color schemes can vary between themes.