Note 12 - Stock-based Compensation - Schedule of Outstanding Un-vested Stock Options (Details)	9 Months Ended
	Apr. 30, 2019 $ / shares shares
Nonvested balance (in shares) | shares	3,479,500
Nonvested, Weighted Average Grant-Date Fair Value (in dollars per share) | $ / shares	$ 0.68
Granted (in shares) | shares	130,000
Granted, Weighted Average Grant-Date Fair Value (in dollars per share) | $ / shares	$ 0.63
Vested options (in shares) | shares	(1,554,250)
Vested, Weighted Average Grant-Date Fair Value (in dollars per share) | $ / shares	$ 0.68
Forfeited options (in shares) | shares	(75,000)
Forfeited, Weighted Average Grant-Date Fair Value (in dollars per share) | $ / shares	$ 0.67
Nonvested balance (in shares) | shares	1,980,250
Nonvested balance, Weighted Average Grant-Date Fair Value (in dollars per share) | $ / shares	$ 0.67