The document discusses the GUI internals of qooxdoo, including its two-pass rendering process of measurement and arrangement. It describes how layout managers compute size hints and do rendering. The queueing system manages widget jobs, state changes, decorator updates, layout computation, DOM flushing, and disposer work. Events are centrally managed with custom dispatchers and support bubbling, capturing, and normalized mouse/keyboard input. Styles and attributes are normalized and synchronized to the DOM.