If we select "HTML if very simple or else PNG" in the [[special:preferences]], and go to a page with the wiki code
<span style="background-color:red;"><math>\pagecolor{red}123456789</math></span>
<math>\pagecolor{red}123456789</math>
<math>123456789</math>
(for example
http://en.wikipedia.org/w/index.php?title=Wikipedia:Sandbox&oldid=370497013
)
the last one is considered "very simple" (since it is converted to text) but the formers are not (and are shown as images).

I think they should still be rendered as text.

FYI the command \pagecolor was enabled in r59550.

Version: unspecified
Severity: enhancement
URL: http://en.wikipedia.org/w/index.php?title=Wikipedia:Sandbox&oldid=370497013