title: SWTBotShell widget not found exception
body: <p>I am writing automated testing using swtBot in eclipse Juno Service Release 2.Below My code   </p>
  
  <pre><code>@BeforeClass
  public static void beforeClass() {
      SWTBotPreferences.KEYBOARD_LAYOUT = "EN_US";
      bot = new SWTWorkbenchBot();
      try {
          bot.viewByTitle("Welcome").close();
      } catch (WidgetNotFoundException e) {
          // ignore
      }
      bot.menu("Window").menu("Preferences").click();
      SWTBotShell shell = bot.shell("Preferences");
      shell.activate();
      SWTBotView view = bot.viewByTitle("Preferences");
  
      bot.tree().expandNode("General").select("Workspace");
      SWTBotCheckBox buildAuto = bot.checkBox("Build automatically");
      if (buildAuto != null &amp;&amp; buildAuto.isChecked())
          buildAuto.click();
      bot.button("Apply").click();
      bot.tree().expandNode("General").select("Perspectives");
      SWTBotRadio radio = bot.radio("Always open");
      if (radio != null &amp;&amp; !radio.isSelected())
          radio.click();
      bot.button("OK").click();
  }
  </code></pre>
  
  <p>I am getting following exception:</p>
  
  <blockquote>
    <p>org.eclipse.swtbot.swt.finder.exceptions.WidgetNotFoundException:
    Could not find shell matching: with text 'Preferences'    at
    org.eclipse.swtbot.swt.finder.SWTBotFactory.waitUntilWidgetAppears(SWTBotFactory.java:387)
      at
    org.eclipse.swtbot.swt.finder.SWTBotFactory.shells(SWTBotFactory.java:114)
      at
    org.eclipse.swtbot.swt.finder.SWTBotFactory.shell(SWTBotFactory.java:104)
      at
    org.eclipse.swtbot.swt.finder.SWTBotFactory.shell(SWTBotFactory.java:95)
      at com.packtpub.e4.junit.plugin.UITest.beforeClass(UITest.java:49)
      at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)  at
    sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)   at
    sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)   at
    java.lang.reflect.Method.invoke(Unknown Source)</p>
  </blockquote>