Loss Per Share (Schedule Of Earnings (Loss) Per Share) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended	9 Months Ended
Jan. 31, 2015	Jan. 31, 2014	Jan. 31, 2015	Jan. 31, 2014
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Net loss	$ (923)us-gaap_NetIncomeLoss	$ (878)us-gaap_NetIncomeLoss	$ (1,146)us-gaap_NetIncomeLoss	$ (1,721)us-gaap_NetIncomeLoss
Dividends paid and payable on preferred stock				(66)
Net loss available to common stockholders	$ (923)	$ (878)	$ (1,146)	$ (1,787)
Weighted-average shares of common stock outstanding, basic	16,384	16,384	16,384	16,022
Effect of dilutive securities
Weighted-average shares of common stock outstanding, diluted	16,384	16,384	16,384	16,022
Basic	$ (0.06)us-gaap_EarningsPerShareBasic	$ (0.05)us-gaap_EarningsPerShareBasic	$ (0.07)us-gaap_EarningsPerShareBasic	$ (0.11)us-gaap_EarningsPerShareBasic
Diluted	$ (0.06)us-gaap_EarningsPerShareDiluted	$ (0.05)us-gaap_EarningsPerShareDiluted	$ (0.07)us-gaap_EarningsPerShareDiluted	$ (0.11)us-gaap_EarningsPerShareDiluted
Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of antidilutive securities	1,847	1,465	1,847	1,621
Warrant [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of antidilutive securities	719	909	719	909

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

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