Note 7 - Stockholders' Equity - Stock Options Activity (Details) - USD ($)	12 Months Ended
Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2017
Outstanding, options (in shares)	6,827,225	4,545,097
Outstanding, weighted-average exercise price (in dollars per share)	$ 1.11	$ 1.42
Outstanding, weighted-average remaining contractual life (Year)	3 years 36 days	3 years 292 days	2 years 328 days
Outstanding, aggregate intrinsic value	$ 20,375		$ 176,575
Granted, options (in shares)	655,000	2,647,500
Granted, weighted-average exercise price (in dollars per share)	$ 0.74	$ 0.76
Exercised, options (in shares)
Exercised, weighted-average exercise price (in dollars per share)
Forfeited, options (in shares)
Forfeited, weighted-average exercise price (in dollars per share)
Expired, options (in shares)	(70,625)	(365,312)
Expired, weighted-average exercise price (in dollars per share)	$ 1.26	$ 2.35
Outstanding, options (in shares)	7,411,600	6,827,225	4,545,097
Outstanding, weighted-average exercise price (in dollars per share)	$ 1.08	$ 1.11	$ 1.42
Exercisable, options (in shares)	7,411,600
Exercisable, weighted-average exercise price (in dollars per share)	$ 1.08
Exercisable, weighted-average remaining contractual life (Year)	3 years 36 days
Exercisable, aggregate intrinsic value	$ 20,375

The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

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Number of options or other stock instruments for which the right to exercise has lapsed under the terms of the plan agreements.

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The number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan.

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Gross number of share options (or share units) granted during the period.

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Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding.

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Number of options outstanding, including both vested and non-vested options.

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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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Weighted average price at which option holders acquired shares when converting their stock options into shares.

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Weighted average price at which grantees could have acquired the underlying shares with respect to stock options of the plan that expired.

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Weighted average price at which grantees could have acquired the underlying shares with respect to stock options that were terminated.

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Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

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Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of vested portions of options outstanding and currently exercisable.

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Weighted average remaining contractual term for vested portions of options outstanding and currently exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Number of share options (or share units) exercised during the current period.

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