title: F5 refresh not always available/working in eclipse
body: <p>Usually if I want to refresh a project (or folder, Working Set, ...) in eclipse I just select the project and hit <kbd>F5</kbd>. Sometimes however nothing happens after hitting <kbd>F5</kbd>. When I then right-click the project I see in the context menu the option <code>Refresh</code> and not <code>Refresh... (F5)</code>.   </p>
  
  <p>So for some reason the current state or such of the project does not allow <kbd>F5</kbd> to refresh. I have this issue now in Indigo but this was already there in at least the 2 previous versions of eclipse. </p>
  
  <p>Is this a bug or is there a (valid) reason why <kbd>F5</kbd> is sometimes not available?</p>