Note 11 - Stock Options and Incentive Plans - Restricted Stock Options Activity (Details) - $ / shares	9 Months Ended	12 Months Ended
	Jan. 31, 2023	Apr. 30, 2022	Apr. 30, 2021
Outstanding, shares (in shares)			7,900,000
Outstanding, weighted average fair value (in dollars per share)			$ 0.42
Forfeited, shares (in shares)	(875,000)	(50,000)	(50,000)
Forfeited, weighted average fair value (in dollars per share)	$ 0.40	$ 0.40	$ 0.40
Outstanding, shares (in shares)	6,925,000
Outstanding, weighted average fair value (in dollars per share)	$ 0.43