ToastOverlay 
    class ToastOverlay(val adwToastOverlayPointer: <Error class: unknown class><<Error class: unknown class>>)(source)
A widget showing toasts above its content.
 
Much like class@Gtk.Overlay, AdwToastOverlay is a container with a single main child, on top of which it can display a class@Toast, overlaid. Toasts can be shown with method@ToastOverlay.add_toast.
See class@Toast for details.
CSS nodes
toastoverlay
├── [child]
├── toast
┊   ├── widget
┊   │   ├── [label.heading]
    │   ╰── [custom title]
    ├── [button]
    ╰── button.circular.flatContent copied to clipboard
AdwToastOverlay's CSS node is called toastoverlay. It contains the child, as well as zero or more toast subnodes.
Each of the toast nodes contains a widget subnode, optionally a button subnode, and another button subnode with .circular and .flat style classes.
The widget subnode contains a label subnode with the .heading style class, or a custom widget provided by the application.
Accessibility
AdwToastOverlay uses the GTK_ACCESSIBLE_ROLE_TAB_GROUP role.