Aquamacs hangs using ESS when calling uncomment-region in .Rnw file

[Michael Braun]

Consider a file with a .Rnw extension, with a LaTeX major mode, and Noweb and NWFL minor modes. The uncomment-region command works fine with general text and text-like environments (e.g., itemize).  However, when calling uncomment-region on a region that includes a math environment (e.g., align, eqnarray), the entire Aquamacs process hangs, requiring a Force Quit.  For example:

\documentclass{article}
\usepackage{amsmath}

\begin{document}

On the following equation, try comment-region, and then uncomment-region. On my system, the uncomment-region call is what hangs the process.

\begin{align}
  1+1=2
\end{align}

\end{document}


This problem occurs with Aquamacs 3.3 and 3.4dev (latest nightly build), but not Aquamacs 3.2, nor with non-Aquamacs emacs. It does occur with less versions 16.04 and 16.10. 

When I toggle ess-noweb-font-lock-mode off, or even just toggle font-lock-mode on, the problem with uncomment-region disappears. So it looks like there is an issue with how ess-noweb-font-lock-mode interacts with Aquamacs.  I don't know which.  Of course, disabling ess-noweb-font-lock-mode means that I lose the font-lock features.

Can you help me resolve this problem?

Thanks,

Michael Braun
braunm at smu.edu