pub fn titlebar(ui: &mut Ui<'_>, title: &str)Expand description
A cross-platform titlebar: a full-width drag strip with the window title
left-aligned next to the window controls. Reads env.window and adapts
by itself — under macOS custom chrome it insets past the native traffic
lights and draws no buttons; under custom chrome elsewhere it appends
minimize/maximize/close; under native decorations it is just a drag
strip (no duplicate buttons).
Typical use, as the first child of a full-height root:
widgets::titlebar(ui, "my app").