Note 5 - Accounts Receivable, Net, Contract Asset and Contract Liability (Details Textual) - USD ($) $ in Thousands	3 Months Ended
	Jul. 31, 2023	Jul. 31, 2022	Apr. 30, 2023
Accounts Receivable, after Allowance for Credit Loss	$ 3,260		$ 3,793
Accounts Receivable, Allowance for Credit Loss	205		205
Contract with Customer, Asset, after Allowance for Credit Loss	3,169		$ 1,893
Increase (Decrease) in Contract with Customer, Asset	1,276	$ (326)
Increase (Decrease) in Contract with Customer, Liability	$ 3,225	$ 3,344