Note 12 - Equity Transaction and Stock-based Compensation - Share-based Compensation, Shares Authorized under Stock Option Plans, by Exercise Price Range (Details) - $ / shares	12 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2017
Range of Exercise Price, Lower Limit (in dollars per share)	$ 0.09
Range of Exercise Price, Upper Limit (in dollars per share)	$ 0.25
Outstanding (in shares)	3,761,500	2,439,250	2,718,183
Weighted Average Exercise Price, Outstanding (in dollars per share)	$ 0.16	$ 0.29	$ 0.29
Weighted Average Remaining Contractual Life (Year)	8 years 182 days
Exercisable (in shares)	2,863,800	2,439,250
Weighted Average Exercise Price, Exercisable (in dollars per share)	$ 0.14	$ 0.11
Range One [Member]
Range of Exercise Price, Lower Limit (in dollars per share)	0.09
Range of Exercise Price, Upper Limit (in dollars per share)	$ 0.10
Outstanding (in shares)	1,741,000
Weighted Average Exercise Price, Outstanding (in dollars per share)	$ 0.09
Weighted Average Remaining Contractual Life (Year)	5 years 292 days
Exercisable (in shares)	1,741,000
Weighted Average Exercise Price, Exercisable (in dollars per share)	$ 0.09
Range Two [Member]
Range of Exercise Price, Lower Limit (in dollars per share)	0.21
Range of Exercise Price, Upper Limit (in dollars per share)	$ 0.21
Outstanding (in shares)	1,470,500
Weighted Average Exercise Price, Outstanding (in dollars per share)	$ 0.21
Weighted Average Remaining Contractual Life (Year)	9 years 328 days
Exercisable (in shares)	747,800
Weighted Average Exercise Price, Exercisable (in dollars per share)	$ 0.21
Range Three [Member]
Range of Exercise Price, Lower Limit (in dollars per share)	0.23
Range of Exercise Price, Upper Limit (in dollars per share)	$ 0.25
Outstanding (in shares)	550,000
Weighted Average Exercise Price, Outstanding (in dollars per share)	$ 0.23
Weighted Average Remaining Contractual Life (Year)	7 years 146 days
Exercisable (in shares)	375,000
Weighted Average Exercise Price, Exercisable (in dollars per share)	$ 0.23