No. I tried to create a formula editor as inkscape extension but stopped this approach
because I was not able to get the size information.
Now I use another approach that works with pyton and qt text elements:
http://sourceforge.net/projects/ikwed (first version is not finished yet).

Hello, how can I get the pixel length of a text element in an extension? Is it possible to access the svg dom function "getComputedTextLength" ? I found a python example here: http://wiki.inkscape.org/wiki/index.php/PythonEffectTutorial and added a msgbox command to show me some text infor...