title: g++ include all /usr/include recursively
body: <p>I'm trying to compile a simple program, with </p>
  
  <pre><code>#include &lt;gtkmm.h&gt;
  </code></pre>
  
  <p>The path to <code>gtkmm.h</code> is <code>/usr/include/gtkmm-2.4/gtkmm.h</code>. g++ doesn't see this file unless I specifically tell it <code>-I /usr/include/gtkmm-2.4</code>.</p>
  
  <p>My question is, how can I have g++ automatically look recursively through all the directories in <code>/usr/include</code> for all the header files contained therein, and why is this not the default action?</p>