title: Drawing a line with open GL
body: <p>I am a newbie with OpenGL. I need to draw a line with it. I browsed the web and found this code:</p>
  
  <pre><code>glBegin(GL_LINES);
  glVertex2f(.25,0.25);
  glVertex2f(.75,.75);
  glEnd();
  </code></pre>
  
  <p>However, I don't see any line. The consoler  appears only for some milliseconds. I need a program that will draw a line and at least visible for some moments.
  Thanks in advance.</p>