Dear ImGui Development & Architecture Guide

[!NOTE]

Dear ImGui is an immediate-mode GUI framework designed for fast iterations, minimal state overhead, and high responsiveness. This guide documents best practices and conventions for writing maintainable, performant, and testable UI code across MuJoCo, its Python bindings, and dependent targets in C++, Python, and WebViewer.

Applies to both C++ and Python: All architectural guidelines, widget patterns, Tables API usage, ID stack rules (## vs ###), and performance principles apply equally whether authoring native C++ (ImGui::) or Python (imgui.) code. While snippets frequently illustrate patterns in Python for concise readability, the corresponding immediate-mode concepts, widget APIs, ID stack mechanics, clipper usage, and styling rules translate directly 1-to-1 to C++. Guidelines apply both to core Dear ImGui and extension libraries, most importantly ImPlot.