src/vs/workbench/browser/layoutState.ts/LayoutStateModel/loadKeyFromStorage
class LayoutStateModel:	private loadKeyFromStorage<T extends StorageKeyType>(key: WorkbenchLayoutStateKey<T>): T | undefined {
		let value: any = this.storageService.get(`${LayoutStateModel.STORAGE_PREFIX}${key.name}`, key.scope);

		if (value !== undefined) {
			switch (typeof key.defaultValue) {
				case 'boolean': value = value === 'true'; break;
				case 'number': value = parseInt(value); break;
				case 'object': value = JSON.parse(value); break;
			}
		}

		return value as T | undefined;
	}