<rect id="c1" x="510"
y="120" width="20px" height="20px" fill="pink" stroke="blue" onclick="setPenColour(evt)"/>
  <![CDATA[
  function setPenColour(evt) {
    m_pen_colour = evt.target.getAttribute('fill');
  }
  ]]>

Reference:
Tutorials - SVG [kevlindev.com]
Tutorials - SVG - Events [kevlindev.com]

The following code used with the ProjectX API informs the client web browser that the whiteboard will be refreshed in 5 seconds. It then archives the current whiteboard information, formats it, and sends a message to each web browser to refresh their view.

<project name="whiteboardqueue">
  <methods>
    <method name="create">
      <params>
        <param var="type">ecmascript</param>
        <param var="body">startRefresh(5)</param>
        <param var="sender">system</param>
      </params>
    </method>
    <method name="timer">
      <params>
        <param var="timer">5</param>
      </params>
    </method>
    <method name="archive_and_format">
      <params/>
    </method>
    <method name="create">
      <params>
        <param var="type">ecmascript</param>
        <param var="body">reloadDocument()</param>
        <param var="sender">system</param>
      </params>
    </method>
  </methods>
</project>

*update 1:14am*
The whiteboard demo [rorbuilder.info] allows the user to draw using the mouse within the web browser which renders SVG. Tested on Flock and Firefox.

*update 4:42pm 28 Mar 08*
You can also view the whiteboard message queue [rorbuilder.info].

*update 6:29pm Mar 08*
I've created a short url (http://rubyurl.com/vxHD) (to demonstrate the cleaning of the whiteboard) which redirects to this http://rorbuilder.info/api/projectx.cgi?xml_project=<project name="whiteboardqueue"><methods><method name="create"><params><param var="type">ecmascript</param><param var="body">startRefresh(5)</param><param var="sender">system</param></params></method><method name="timer"><params><param var="timer">5</param></params></method><method name="archive_and_format"><params/></method><method name="create"><params><param var="type">ecmascript</param><param var="body">reloadDocument()</param><param var="sender">system</param></params></method></methods></project>

I've