src/vs/workbench/contrib/themes/browser/themes.contribution.ts/toEntry
function toEntries(themes: Array<IWorkbenchTheme>, label?: string): QuickPickInput<ThemeItem>[] {
	const toEntry = (theme: IWorkbenchTheme): ThemeItem => ({ id: theme.id, label: theme.label, description: theme.description });
	const sorter = (t1: ThemeItem, t2: ThemeItem) => t1.label.localeCompare(t2.label);
	let entries: QuickPickInput<ThemeItem>[] = themes.map(toEntry).sort(sorter);
	if (entries.length > 0 && label) {
		entries.unshift({ type: 'separator', label });
	}
	return entries;
}