Note 15 - Segment Reporting and Sales by Major Customer - Professional Services (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Oct. 31, 2022	Oct. 31, 2021	Oct. 31, 2022	Oct. 31, 2021
Revenues from customers	$ 19,326	$ 18,649	$ 34,629	$ 36,393
Interest expense	707	640	1,430	1,254
Depreciation and amortization	756	705	1,527	1,407
Operating income (loss)	4,002	4,743	5,627	8,765
Gaming [Member]
Revenues from customers	9,674	9,129	18,567	18,393
Interest expense	622	576	1,264	1,124
Depreciation and amortization	608	574	1,234	1,152
Operating income (loss)	2,939	3,075	5,581	6,619
Aircraft Modification [Member]
Revenues from customers	5,878	5,910	9,714	11,692
Interest expense	66	53	132	108
Depreciation and amortization	58	44	111	89
Operating income (loss)	912	1,245	966	2,388
Aircraft Avionics [Member]
Revenues from customers	523	665	1,237	1,540
Interest expense	0	0	0	0
Depreciation and amortization	3	1	5	3
Operating income (loss)	(249)	(114)	(201)	(133)
Special Mission Electronics [Member]
Revenues from customers	3,180	2,842	4,971	4,604
Interest expense	11	5	18	11
Depreciation and amortization	36	37	75	70
Operating income (loss)	1,451	1,485	2,067	1,988
Product and Service, Other [Member]
Revenues from customers	71	103	140	164
Interest expense	8	6	16	11
Depreciation and amortization	51	49	102	93
Operating income (loss)	$ (1,051)	$ (948)	$ (2,786)	$ (2,097)