Dear ImGui Immediate Mode GUI

Dear ImGui is a bloat-free graphical user interface library for C++ designed for creating tooling, debugging interfaces, and data visualization in applications where performance and simplicity are paramount. Created by Omar Cornut in 2014, Dear ImGui has become one of the most popular UI libraries for game development and tools with over 60,000 stars. Key features: immediate mode paradigm where the entire UI is described and rendered every frame from code, with no retained widget tree, no state synchronization, and no message handling boilerplate. Minimalistic design with a single-header include approach and zero external dependencies, requiring only a rendering backend for drawing vertices and textures. Highly performant: optimized vertex generation and draw call batching for 60fps+ rendering with thousands of widgets. Over 20 rendering backends including OpenGL, Vulkan, DirectX 9-12, Metal, WebGPU, and software rasterizers. Widget library including windows, buttons, sliders, checkboxes, radio buttons, combo boxes, list boxes, color pickers, plots, tables, trees, tabs, menus, tooltips, progress bars, separators, and custom drawable canvases. Docking and multi-viewport support for creating professional IDE-like interfaces with dockable panels and multiple OS windows. Theming system with customizable colors, rounding, padding, and fonts, including support for custom font files and icons (Font Awesome, Material Design Icons). Layout system with automatic sizing and positioning, plus flexible layout using SameLine, columns, and groups. Input handling for mouse, keyboard, gamepad, and multi-touch. Plotting widgets for real-time data visualization (lines, histograms, custom). Tables with sorting, resizing, and hierarchical rows. Cross-platform on Windows, macOS, Linux, Android, iOS, and WebAssembly. Used by game engines, media tools (Blender, OBS), and developer tools worldwide. Open source under MIT license.