6. Equity Compensation Plans (Details Narrative) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
Apr. 30, 2021	Apr. 30, 2020	Apr. 30, 2019
Stock reserved for issuance	14,142,000
Proceeds from exercise of stock options	$ 3,600	$ 900	$ 1,300
Employee Stock Purchase Plan [Member]
Stock issued during period, ESPP	72,409	47,526	75,148
ESPP weighted average purchase price	$ 5.84	$ 3.94	$ 3.44
Weighted average grant date fair value, other than options	3.17	1.81	1.49
Stock Option [Member]
Weighted-average grant date fair value of options granted	$ 4.74	$ 3.74	$ 3.30
Aggregate intrinsic value of stock options exercised	$ 3,900	$ 700	$ 500
Unrecognized compensation costs related to non-vested stock options	$ 5,500
Unrecognized compensation cost weighted average vesting period	2 years 6 months 18 days
RSUs [Member]
Unrecognized compensation cost weighted average vesting period	2 years 7 months 21 days
Fair value of RSUs vested	$ 700	$ 300
Unrecognized compensation cost related to non-vested RSUs	$ 2,800
Weighted average grant date fair value, other than options	$ 7.29	$ 5.91	$ 4.28
Stock Incentive Plans [Member]
Stock reserved for issuance	6,290,000
Stock Incentive Plans [Member] \| Options and RSU's [Member]
Stock reserved for issuance	3,689,364
Stock Incentive Plans [Member] \| Future Grants [Member]
Stock reserved for issuance	2,600,193
Employee Stock Purchase Plan [Member]
Stock reserved for issuance	1,076,000

Aggregate number of common shares reserved for future issuance.

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