Q:

Why does not overflow="linebreak" not work with MathML?

In the following case with MathML, I cannot get linebreaking to work. In particular, I would like linebreaking to work inside of an <mtext> element inside of an <mrow> element inside of an <mtable>.
But, as can be seen with the following minimal (non-working) example, it is not working (on JSFiddle):
The HTML:
<script src="http://cdn.mathjax.org/mathjax/latest/MathJax.js?config=TeX-AMS-MML_HTMLorMML"></script>

<div id="test">
    <math overflow="linebreak">
        <mtable>
            <mrow><mtext>Lorem ipusm lorem ipsum Lorem ipsum lorem ipsum Lorem ipsum lorem ipsum</mtext></mrow>
        </mtable>
    </math>
</div>

<div id="test">
    Lorem ipusm lorem ipsum Lorem ipsum lorem ipsum Lorem ipsum lorem ipsum
</div>

And the CSS:
#test{
    border: 2px solid black;
    width: 11em;
    padding: 1em;
}

How can I get linebreaking to work, so that the first <div> looks like the second <div>?

A:

MathJax linebraking is controlled through the MathJax configuration (see the documentation for details).  MathJax doesn't currently implement the overflow attribute for the <math> element (this is on the to-do list).
Even with line breaking turned on, however, MathJax only breaks between elements, so will not wrap the content of an <mtext> element (this is also on the to-do list).  MathJax is intended for mathematical typesetting, not textual typesetting, so using it for wrapped paragraphs as in your example is outside its scope.
Note that your MathML is invalid, as the <mrow> should be <mtr> and the only children allowed for <mtr> are <mtd> elements.  So your <mtext> would need to be enclosed in an <mtd>.
Finally, your HTML is also invalid, as an ID is only allowed to appear once in an HTML file, so id="test" should not appear on two separate <div> elements.  For this type of situation, you should be using classes, not ID's.

