6. Net Loss per Common Share (Details - Antidilutive shares, conversion price) - shares shares in Thousands	3 Months Ended		9 Months Ended
	Jan. 31, 2020	Jan. 31, 2019	Jan. 31, 2020	Jan. 31, 2019
Dilutive effect of shares on diluted shares outstanding	347	156	232	204
If Converted Method [Member]
Dilutive effect of shares on diluted shares outstanding	4,085	4,805	4,708	4,671
If Converted Method [Member] | Stock Options [Member]
Dilutive effect of shares on diluted shares outstanding	2,106	2,779	2,721	2,659
If Converted Method [Member] | RSUs [Member]
Dilutive effect of shares on diluted shares outstanding	0	47	8	16
If Converted Method [Member] | Warrants
Dilutive effect of shares on diluted shares outstanding	0	0	0	17
If Converted Method [Member] | Series E Preferred Stock [Member]
Dilutive effect of shares on diluted shares outstanding	1,979	1,979	1,979	1,979