Note 3 - Accounts Receivable, Net, Contract Asset and Contract Liability (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2023	Apr. 30, 2022
Accounts Receivable, after Allowance for Credit Loss	$ 3,793	$ 3,636
Accounts Receivable, Allowance for Credit Loss	205	205
Contract with Customer, Asset, after Allowance for Credit Loss	1,893	1,470
Increase (Decrease) in Contract with Customer, Asset	423	1,049
Increase (Decrease) in Contract with Customer, Liability	5,211	(4,978)
Contract with Customer, Liability, Revenue Recognized	$ 820	$ 5,798