Note 1 - Significant Accounting Policies - Allowance for Doubtful Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Apr. 28, 2018	Apr. 29, 2017	Apr. 30, 2016
Balance at beginning of year	$ 468	$ 484	$ 330
Net charge to expense	34	74	232
Net charge-off	(50)	(90)	(78)
Balance at end of year	$ 452	$ 468	$ 484