 maintains a tree of graphical music elements. Each element has a bounding box and a date. The library includes the necessary to browse this tree and to retrieve elements by date or position.</li>
</ul>
<h2><a class="anchor" id="devices"></a>
Graphic devices</h2>
<p>First version of the GUIDO Engine was Windows dependent: a Windows HDC type (graphic device context handle) was provided to the GGR objects, that were directly calling Microsoft Windows APIs to draw graphics and text.</p>
<p>For the GUIDO Engine