Note 1 - Significant Accounting Policies - Allowance for Doubtful Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Apr. 27, 2019	Apr. 28, 2018	Apr. 29, 2017
Balance at beginning of year	$ 452	$ 468	$ 484
Net charge to expense	87	34	74
Net charge-off	(23)	(50)	(90)
Balance at end of year	$ 516	$ 452	$ 468