GitHub Desktop's comparison graph is a sophisticated user interface component central to managing branch interactions and visualizing changes against a base branch. It was developed as a reusable web component within an Electron app, allowing it to be integrated across OS X and Windows platforms by using WebView and CefSharp respectively. This cross-platform approach utilizes shared code for ease of development, while specific implementations differ due to platform-specific APIs. The graph's API is designed to be narrow and focused, facilitating its maintenance and integration. The shared architecture enables iterative development, allowing GitHub for Mac and Windows to converge into GitHub Desktop without a complete rewrite, thus enabling continuous updates and improvements. The project emphasizes maintaining platform-specific user experiences with CSS shims, ensuring a tailored look and feel while benefiting from shared development efforts.