[O] BEAMER_act and special environments

[James Harkins]

Hi,

I'm not especially familiar with emacs-lisp and I haven't looked at the 
functions for node properties at all. Unfortunately, I'm under a time 
crunch today and I don't have the few hours it would take to get up to 
speed (otherwise, I'd have a go at it myself).

It seems that everything in org-beamer-environments-default supports 
overlay specifications, except beamercolorbox. OK... what about 
org-beamer-environments-special? I found today that B_columns ignores any 
overlay specification given in the heading's properties. That is:

**** Header                                                       :B_columns:
    :PROPERTIES:
    :BEAMER_env: columns
    :BEAMER_act: 2-
    :END:
(... with some BMCOL headings underneath...)

-->

\begin{columns}
.. blah blah...
\end{columns}

.. where I would have hoped for "\begin{columns}<2->"

I was able to work around the limitation by wrapping the "columns" 
environments within "onlyenv" environments. But it seems to me that it 
might be nicer to be able to write the overlay directly into the affected 
environment.

I don't mind poking around the code, but I'd need some tips. I can see 
where B_columns gets formatted, but I'm not clear how to check for a 
BEAMER_act property.

Thanks,
hjh