src/vs/workbench/contrib/themes/browser/themes.contribution.ts/openExtensionViewlet
function openExtensionViewlet(viewletService: IViewletService, query: string) {
	return viewletService.openViewlet(VIEWLET_ID, true).then(viewlet => {
		if (viewlet) {
			(viewlet?.getViewPaneContainer() as IExtensionsViewPaneContainer).search(query);
			viewlet.focus();
		}
	});
}