els can be used as if they were <a href="../api/symbols/Panel.html" target="api">Panel</a>-derived classes in calls to <a href="../api/symbols/GraphObject.html#make" target="api">GraphObject.make</a>.
They are implemented as simple visual trees of <a href="../api/symbols/GraphObject.html" target="api">GraphObject</a>s in <a href="../api/symbols/Panel.html" target="api">Panel</a>s,
with pre-set properties and event handlers.
</p>
<p>
More information can be found in the <a href="../intro/buttons.html">GoJS I