src/vs/workbench/browser/panel.ts/Panel/mergeSecondaryActions
class Panel:	private mergeSecondaryActions(actions: readonly IAction[], panelActions: IAction[]): readonly IAction[] {
		if (panelActions.length && actions.length) {
			return [
				...actions,
				new Separator(),
				...panelActions,
			];
		}
		return panelActions.length ? panelActions : actions;
	}