title: Eclipse - How to set default System Library
body: <p>Workspace default JRE shows the one that I set via <code>Window -&gt; preferences -&gt; Java -&gt; Installed JREs</code>. 
   But by default, the project has JRE System Library as Execution environment <code>[JavaSE-1.6(jre6)]</code>. 
  Why doesn't JRE System Library make Workspace default JRE as the default System Library? And how can I change it to default System Library?</p>
  
  <p><img src="https://i.stack.imgur.com/eHWHU.png" alt="enter image description here"></p>