Both the Dia and Dot digrams render/display correctly in Internet Explorer (IE 11).

With Firefox (26.0), the Dot diagram displays correctly but the Dia does not.

The new Dia handler is inserting an absolute rather than relative path, which Firefox considers a security issue.
See also http://stackoverflow.com/questions/13802244/firefox-doesnt-show-image-on-ie-works-fine

Doing a view source:

   <p><div class="dotgraph">
   <img src="dot_Test.png" alt="dot_Test.png" border="0" usemap="#dot_Test.map"/>
   <map name="dot_Test.map" id="dot_Test.map"></map>
   <div class="caption">
   This is a Dot test</div>
   </div>

vs. 

   <p>Generated .png does not display correctly in FireFox 26.0, but does for IE 11.</p>
   <p><div class="diagraph">
   <img src="C:/temp/diaTest/html/dia_Test.png" />
   <div class="caption">
   This is a Dia test</div>
   </div>

