Expand description
Manages the application lifecycle, including window creation and event handling.
This module is the OS shell. It owns the winit event loop, the windows,
and the DrawSink each one presents through, and knows nothing about the
browser: all browser interaction goes through the BrowserHost port
declared in super::shell.
This is the only place that constructs a concrete sink. Everything above it
— including the whole browser layer — sees DrawSink as a trait object.