title: Incremental Build: Eclipse CDT does not notice that source has changed
body: <p>When clicking the "Build" symbol in Eclipse CDT, it is supposed to build only the source files which have changed. A very annoying behavior of Eclipse CDT is that it very often ignores that "minor" changes have been made, but it is not clear what minor means.</p>
  
  <p>The output then is</p>
  
  <pre><code>13:21:06 **** Incremental Build of configuration &lt;config&gt; for project &lt;proj&gt; ****
  make all 
  make: Nothing to be done for `all'.
  </code></pre>
  
  <p>The only way for me to test the changes I just made is then to clean and completely rebuild the entire project, which wastes a lot of time.</p>
  
  <p>What could be the problem here and how can I fix incremental building?</p>
  
  <p>EDIT: Could it be that not minor, but very recent changes are ignored because of some clock synchronization issue?</p>