Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Oct. 31, 2016	Oct. 31, 2015	Oct. 31, 2016	Oct. 31, 2015
Income Statement [Abstract]
Revenue	$ 50,408	$ 49,926	$ 100,501	$ 98,802
Cost of revenue	18,855	19,146	37,611	38,694
Gross profit	31,553	30,780	62,890	60,108
Operating expenses:
Sales and marketing	15,819	16,502	31,123	35,668
Research and development	9,959	10,354	21,032	20,887
General and administrative	8,051	7,643	16,310	15,881
Restructuring charges	767	0	1,094	0
Acquisition-related and other	120	224	296	926
Amortization of acquired intangible assets	310	310	619	619
Total operating expenses	35,026	35,033	70,474	73,981
Operating loss	(3,473)	(4,253)	(7,584)	(13,873)
Other income (expense), net:
Interest income	153	74	295	151
Interest expense	(459)	(461)	(948)	(1,032)
Other expense	(263)	(88)	(775)	(306)
Total other expense, net	(569)	(475)	(1,428)	(1,187)
Loss before income taxes	(4,042)	(4,728)	(9,012)	(15,060)
Income tax expense	92	124	227	36
Net loss	$ (4,134)	$ (4,852)	$ (9,239)	$ (15,096)
Net loss per share:
Basic and diluted loss per share	$ (0.05)	$ (0.06)	$ (0.11)	$ (0.19)
Basic and diluted weighted average number of shares outstanding	82,930	80,678	82,572	80,426