Accessibility
DrawerHost is a non-modal dialog. The accessible name is the active drawer's title. The heading is an h2. The close control's name is closeLabel.
nav.label. Arrow keys move between segments. Each segment is named by its label.Cancel a cancelable close with details.cancel() when a parent owns Escape, such as a confirm dialog inside the drawer. An outside press reports light-dismiss. Keep open true to ignore it.
The dialog is in the trigger's owner document, including a pop-out opened with window.open. When that window changes, the drawer closes.