Revenue by geographic location (Details) - USD ($)		12 Months Ended
		Apr. 30, 2015		Apr. 30, 2014
Revenues		$ 28,258,000		$ 30,399,000
Total assets		6,275,000		7,572,000
Long lived assets		1,498,000		1,353,000
United States
Revenues		23,285,000		24,917,000
Total assets		6,269,000		7,556,000
Long lived assets		1,498,000		1,353,000
Europe
Revenues		3,785,000		3,431,000
Total assets		6,000		16,000
Long lived assets		0		0
Other
Revenues	[1]	1,188,000		2,051,000
Total assets	[1]	0		0
Long lived assets		$ 0	[1]	$ 0

[1] Principally Asia Pacific Region