Note 10 - Stock Options and Incentive Plans - Restricted Stock Options Activity (Details) - $ / shares	12 Months Ended
	Apr. 30, 2022	Apr. 30, 2021
Outstanding, shares (in shares)		7,500,000
Outstanding, weighted average fair value (in dollars per share)		$ 0.40
Forfeited during the year ended April 30, 2021 (in shares)	(50,000)	(50,000)
Forfeited during the year ended April 30, 2021 (in dollars per share)	$ 0.40	$ 0.40
Outstanding, shares (in shares)	7,400,000
Outstanding, weighted average fair value (in dollars per share)	$ 0.40