CONSOLIDATED STATEMENT OF CHANGES IN STOCKHOLDERS’ EQUITY - USD ($) $ in Thousands	Total	Common Stock	Treasury Stock	Additional Paid-in Capital	Accumulated Deficit
Balance at Apr. 30, 2017	$ 400	$ 11	$ (1,252)	$ 70,991	$ (69,350)
Balance (in shares) at Apr. 30, 2017		10,982,159	269,685
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	1,004			1,004
Issuance of common stock for services	37			37
Issuance of common stock (in shares)		8,569
Issuance of common stock on exercise of stock options and warrants	38			38
Issuance of common stock on exercise of stock options and warrants (in shares)		12,500
Net income (loss)	(1,476)				(1,476)
Balance at Apr. 30, 2018	3	$ 11	$ (1,252)	72,070	(70,826)
Balance (in shares) at Apr. 30, 2018		11,003,228	269,685
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	636			636
Issuance of common stock for services	6			6
Issuance of common stock (in shares)		5,462
Issuance of common stock on exercise of stock options and warrants	1,465	$ 1	$ 1,252	212
Issuance of common stock on exercise of stock options and warrants (in shares)		610,848	(269,685)
Net income (loss)	128				128
Balance at Apr. 30, 2019	$ 2,238	$ 12	$ 0	$ 72,924	$ (70,698)
Balance (in shares) at Apr. 30, 2019		11,619,538	0