src/vs/workbench/contrib/preferences/browser/settingsTreeModels.ts/SettingsTreeSettingElement/matchesAllLanguages
class SettingsTreeSettingElement:	matchesAllLanguages(languageFilter?: string): boolean {
		if (!languageFilter) {
			// We're not filtering by language.
			return true;
		}

		if (!this.languageService.isRegisteredLanguageId(languageFilter)) {
			// We're trying to filter by an invalid language.
			return false;
		}

		// We have a language filter in the search widget at this point.
		// We decide to show all language overridable settings to make the
		// lang filter act more like a scope filter,
		// rather than adding on an implicit @modified as well.
		if (this.setting.scope === ConfigurationScope.LANGUAGE_OVERRIDABLE) {
			return true;
		}

		return false;
	}