title: GWT runtime UserAgent and compile time UserAgent mismatch
body: <p>I recently change gwt.xml script to only compile 1 permutation(ie8 only), This solve my previous issue, however there is a cosmetic issue arise, which is a annoying popup window shows up every time opening my GWT page with IE8</p>
  
  <p>Here i include the screenshot showing the popup, any help to get rid of it will be appreciated.
  <img src="https://i.stack.imgur.com/XzU71.png" alt="enter image description here"></p>
  
  <p>Update: Follow Thomas's advice,i been able to get rid of that message by compile for ie8 and safari. however since then i am only able to open the webpage with my IE9 in IE9 document mode not with IE8 mode, my user is using IE8</p>
  
  <p>Below is code snippet for gwt.xml</p>
  
  <pre><code>    &lt;set-property name="user.agent" value="ie8"/&gt;
  &lt;extend-property name="user.agent" values="safari" /&gt;
  </code></pre>
  
  <p>below is GWT Dev Log showing the exception, user agent 'Mozilla/4.0' does puzzle me as i do have Firefox 14.0.1 installed.</p>
  
  <pre><code> 11:12:17.143 [ERROR] [dca] Failed to load module 'dca' from user agent 'Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.1; WOW64; Trident/4.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; Media Center PC 6.0; InfoPath.3; .NET4.0C; .NET4.0E; MS-RTC LM 8)' at 127.0.0.1:51883
  </code></pre>
  
  <p>i also found there is a Google Chrome Frame plugin for the IE, however since it is company default setting, it would be my last resort. </p>
  
  <p>OK, here is my final update, In default GWT cover 6 permutation include IE8, However my IE has Chromn Frame which mask my browser to safari, IE8 and older browser does not support "AddEventListener" method, which is most GWT widget depend on. Therefore the gwt use safari implementation for my IE8 browser will fault on webpage initialization saying object doesn't support AddEventListener method. </p>
  
  <p>my first attempt is set GWT to only compile for ie8, however this generate the annoying popup shown above, </p>
  
  <p>Second attempt is set GWT to compile both ie8 and safari, again this fault on AddEventListener method</p>
  
  <p>Last attempt is to utilize the Chrome Frame and set </p>
  
  <pre><code>     &lt;meta equiv="X-UA-Compatible" content="chrome=1"&gt; 
  </code></pre>
  
  <p>which let IE browser with Chrome Frame handle webpage using chrome's engine instead of IE engine, which did not do much to me, same story. </p>
  
  <p>My final solution is let GWT compile 6 permutation as default and disable the Chrome Frame, this is company wide default plug in, but if user want this plug in then they should really get the actual chrome let natural selection work its magic.</p>