title: VB6 Picturebox.Line tuple arguments
body: <p>I have just come across a surprising feature of VB6.</p>
  
  <p>The <code>PictureBox</code> control has a method <code>Line</code>:</p>
  
  <blockquote>
    <p>Sub Line(Flags As Integer, X1 As Single, Y1 As Single, X2 As Single, Y2 As Single, Color As Long)</p>
  </blockquote>
  
  <p>But it is usually called like this:</p>
  
  <pre><code>Picture1.Line (lastX, lastY)-(X, Y), vbBlue
  </code></pre>
  
  <p>I never knew this "auto-unbox" feature. And the <code>flags</code> parameter seems to be skipped, but is not <code>Optional</code>.</p>
  
  <p>What sorcery is this? Is this a special feature of this control or of the language? Can other controls use this feature?</p>