Note 3 - Intangible Assets and Goodwill (Detail) - Intangible Assets (USD $) In Thousands, unless otherwise specified	21 Months Ended
	Jan. 31, 2013	Apr. 30, 2012
Gross Carrying Amount	$ 2,897	$ 2,897
Accumulated Amortization	(1,162)	(1,011)
Minimum [Member] | Patents, Trademarks and Copyrights [Member]
Estimated Useful Lives	10
Minimum [Member] | Customer Relationships [Member]
Estimated Useful Lives	5
Minimum [Member] | Trade Names [Member]
Estimated Useful Lives	15
Minimum [Member] | Developed Technology Rights [Member]
Estimated Useful Lives	13
Maximum [Member] | Patents, Trademarks and Copyrights [Member]
Estimated Useful Lives	15
Maximum [Member] | Customer Relationships [Member]
Estimated Useful Lives	15
Maximum [Member] | Developed Technology Rights [Member]
Estimated Useful Lives	15
Patents, Trademarks and Copyrights [Member]
Estimated Useful Lives	-
Gross Carrying Amount	852	852
Accumulated Amortization	(388)	(336)
Customer Relationships [Member]
Estimated Useful Lives	-
Gross Carrying Amount	1,040	1,040
Accumulated Amortization	(433)	(386)
Trade Names [Member]
Gross Carrying Amount	530	530
Accumulated Amortization	(191)	(165)
Developed Technology Rights [Member]
Estimated Useful Lives	-
Gross Carrying Amount	475	475
Accumulated Amortization	$ (150)	$ (124)