title: jsf target="_blank" not working with primefaces commandbutton
body: <p>Trying to open a new tab to accept a generated pdf file from the bean.</p>
  
  <p>Works with h:commandbutton, no tab opened with p.commandbutton.</p>
  
  <p>Tried to put onclick and oncomplete="window.open('_blank') on the p:commandbutton, it opens a new tab but it doesn't get the pdf and gets "Error 404 Not Found".</p>
  
  <p>Using primefaces-3.1</p>
  
  <p>Thanks</p>
  
  <pre><code>  &lt;?xml version="1.0" encoding="UTF-8"?&gt;
      &lt;!DOCTYPE html PUBLIC '-//W3C//DTD XHTML 1.0 Transitional//EN'
       'http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd'&gt;
  
       &lt;html xmlns="http://www.w3.org/1999/xhtml"
        xmlns:h="http://java.sun.com/jsf/html"
        xmlns:f="http://java.sun.com/jsf/core"
        xmlns:p="http://primefaces.org/ui"&gt;
  
  
      &lt;h:head&gt;
          &lt;h:outputStylesheet library="base" name='jquery-ui-1.8.16.custom.css' /&gt;
      &lt;/h:head&gt;
      &lt;h:form target="_blank"&gt;
        &lt;p:commandButton value="Run" action="#{bean.createReport}"  /&gt;
      &lt;/h:form&gt;
  
      &lt;/html&gt;
  </code></pre>