title: OpenGL symbols highlighting error in visual studio code for Mac
body: <p>When I wrote c++ code in vs code for Mac, the editor keeps showing red underline warnings for OpenGL symbols. For example:</p>
  
  <pre><code>#include &lt;OpenGL/gl.h&gt;
  ...
  glDepthMask(GL_TRUE);
  </code></pre>
  
  <p>Meanwhile, I cannot use "Go to Definition" on these OpenGL files and functions. My code is correct and can be successfully compiled.</p>
  
  <p>I tried to add "/System/Library/Frameworks" to "includePath" slot in the file ".vscode/c_cpp_properties.json", but it doesn't work.</p>
  
  <p>Anyway to make this right?</p>