The expanding source panel from createSourceWrapper: a collapsible panel, or a drawer when
options.useDrawerForSources is set. It is open when options.currentlyExpanded marks its key
as expanded, which createSourceButton toggles. Closing the drawer dispatches a
SourceExpansionEvent. Renders nothing when there are no sources.
The expanding source panel from createSourceWrapper: a collapsible panel, or a drawer when
options.useDrawerForSourcesis set. It is open whenoptions.currentlyExpandedmarks its key as expanded, which createSourceButton toggles. Closing the drawer dispatches a SourceExpansionEvent. Renders nothing when there are no sources.