title: difference between geb.env and geb.driver
body: <p>I am trying to find out the difference between geb.driver option against geb.env. </p>
  
  <p>I could not find any concrete documentation on them.  I could understand that geb.env is similar to grails.env except, geb env's are defined in GebConfig.groovy. </p>
  
  <p>Then, why do we need geb.driver.  More confusing stuff is my functional test cases are working fine if I specify geb.driver but getting error when I use geb.env. </p>
  
  <pre><code>Cannot find window: _PPIdentityWindow_ 
  Build info: version: '2.25.0', revision: '17482', time: '2012-07-18 22:18:01' 
  System info: os.name: 'Mac OS X', os.arch: 'x86_64', os.version: '10.7.5', java.version: '1.6.0_35' 
  Driver info: driver.version: unknown 
  org.openqa.selenium.NoSuchWindowException: Cannot find window: _PPIdentityWindow_ 
  Build info: version: '2.25.0', revision: '17482', time: '2012-07-18 22:18:01' 
  System info: os.name: 'Mac OS X', os.arch: 'x86_64', os.version: '10.7.5', java.version: '1.6.0_35' 
  Driver info: driver.version: unknown 
          at org.openqa.selenium.htmlunit.HtmlUnitDriver$HtmlUnitTargetLocator.window(HtmlUnitDriver.java:943) 
          at geb.Browser.switchToWindow(Browser.groovy:458) 
          at geb.Browser.withWindow(Browser.groovy:470) 
          at geb.spock.GebSpec.methodMissing(GebSpec.groovy:51) 
  </code></pre>
  
  <p>Any help is greatly appretiated.  I have asked the same question in grails user mailing list too.</p>
  
  <p><a href="http://grails.1312388.n4.nabble.com/Difference-between-geb-driver-and-geb-env-td4637641.html" rel="nofollow">http://grails.1312388.n4.nabble.com/Difference-between-geb-driver-and-geb-env-td4637641.html</a></p>