title: Precise control of GWT permutations via *.gwt.xml
body: <p>I need to precisely specify GWT permutations and control the variation within them (combinations of property values supported by each) but have hard time finding detailed behaviour specification. </p>
  
  <p>During my experimentation I have learned that I have to watch for creating set-property ... when-property-is cycles even though these cycles are "stable" - i.e. they do not change any part of the cycle, just "confirm" it. That restricted what I can do, so I decided to try another way - define a brand new property, (just) for example:</p>
  
  <pre><code>  &lt;define-property name="precise.permutation" values="webkit,gecko,ie,unsupported"/&gt;
  </code></pre>
  
  <p>... and then have something like:</p>
  
  <pre><code>  &lt;set-property name="precise.permutation" value="webkit"&gt;
      &lt;!-- ... custom conditions ... --&gt;
    &lt;/set-property&gt;
    &lt;set-property name="precise.permutation" value="gecko"&gt;
      &lt;!-- ... custom conditions ... --&gt;
    &lt;/set-property&gt;
    &lt;set-property name="precise.permutation" value="ie"&gt;
      &lt;!-- ... custom conditions ... --&gt;
    &lt;/set&gt;
    &lt;set-property name="precise.permutation" value="unsupported"&gt;
      &lt;!-- ... custom conditions ... --&gt;
    &lt;/set-property&gt;
  </code></pre>
  
  <p>... I then tried restricting this to all but unsupported which is used as an example but is entirely counter-intuitive as it uses the same set-property tag as above: </p>
  
  <pre><code>  &lt;set-property name="precise.permutation" value="webkit,gecko,ie" /&gt;
  </code></pre>
  
  <p>I also had to collapse other properties to make sure that they don't cause additional permutations.</p>
  
  <p>Unfortunately, that does not seem to work as intended (tried with GWT 2.8 RC2). Even though the "unsupported" permutation does not show up (this is desired), the combinations of properties from it reappear in other permutations (which isn't desired). </p>
  
  <p>Can someone help me find authoritative <em>and complete</em> documentation on this or help me figure this out, please?</p>
  
  <p>Thanks!</p>