Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Jan. 31, 2017	Jan. 31, 2016	Jan. 31, 2017	Jan. 31, 2016
Income Statement [Abstract]
Revenue	$ 50,525	$ 50,255	$ 151,026	$ 149,057
Cost of revenue	19,196	18,920	56,807	57,614
Gross profit	31,329	31,335	94,219	91,443
Operating expenses:
Sales and marketing	16,322	16,113	47,445	51,781
Research and development	9,588	10,199	30,620	31,086
General and administrative	7,299	6,940	23,609	22,821
Restructuring charges	0	0	1,094	0
Acquisition-related and other	84	332	380	1,258
Amortization of acquired intangible assets	309	309	928	928
Total operating expenses	33,602	33,893	104,076	107,874
Operating loss	(2,273)	(2,558)	(9,857)	(16,431)
Other income (expense), net:
Interest income	150	124	445	275
Interest expense	(450)	(596)	(1,398)	(1,628)
Other expense	(32)	(247)	(807)	(553)
Total other expense, net	(332)	(719)	(1,760)	(1,906)
Loss before income taxes	(2,605)	(3,277)	(11,617)	(18,337)
Income tax expense (benefit)	123	(163)	350	(127)
Net loss	$ (2,728)	$ (3,114)	$ (11,967)	$ (18,210)
Net loss per share:
Basic and diluted loss per share	$ (0.03)	$ (0.04)	$ (0.14)	$ (0.23)
Basic and diluted weighted average number of shares outstanding	83,348	81,096	82,830	80,649