Last modified: 2014-10-20 09:49:10 UTC
In \underline{\underline a} MathJax makes the second underline to long, the PNG shows both correctly with equal length. By the way: You can have a look the examples for all my bugs at http://leuksman.com/mw/index.php/User:Schnark
Actually, if you look carefully, the 2nd line is actually two lines made up from overlapping − span 86 was the first underline under a, the 2nd underline is span 87, which looks like this: <span style="position: absolute; clip: rect(2.318em 1000em 2.839em -0.572em); top: -1.998em; left: 0em; "><span class="mo" id="MathJax-Span-87" style=""><span style="display: inline-block; position: relative; height: 0px; width: 0.89em; "><span style="position: absolute; font-family: MathJax_Main; top: -4em; left: -0.084em; display:none;">−<span style="display: inline-block; width: 0px; height: 4em; "></span></span><span style="position: absolute; font-family: MathJax_Main; top: -4em; left: 0.196em; display:none;">−<span style="display: inline-block; width: 0px; height: 4em; "></span></span></span></span><span style="display: inline-block; width: 0px; height: 2.778em; "></span></span> I suspect that it is interpreting 'underline a' as two elements and thus underlining both of those elements or something.
confirmed
It seems that something like \uuline (from the ulem package) would be more appropriate for a MathML conversion.
Seems to be a problem within MathJax https://www.mediawiki.org/wiki/Extension:Math/bug/35189
Filed upstream at https://github.com/mathjax/MathJax/issues/937
